Criticism

Critics generally claim three basic disadvantages for presidential systems:

• Tendency towards authoritarianism — some political scientists say that presidentialism is not constitutionally stable. According to some political scientists, such as Fred Riggs, presidentialism has fallen into authoritarianism in nearly every country it has been attempted. Critics such as Dana D. Nelson in her 2008 book Bad for Democracy^[2] see the office of the presidency in the United States as essentially undemocratic^[3] and she sees presidentialism as worship of the presidency by citizens which tends to undermine civic participation.^[3]
• Separation of powers — a presidential system establishes the presidency and the legislature as two parallel structures. Critics argue that this creates undesirable gridlock, and that it reduces accountability by allowing the president and the legislature to shift blame to each other.
• Impediments to leadership change — it is claimed that the difficulty in removing an unsuitable president from office before his or her term has expired represents a significant problem.

Tendency towards authoritarianism

Winning the presidency is a winner-take-all, zero-sum prize. A prime minister who does not enjoy a majority in the legislature will have to either form a coalition or, if he is able to lead a minority government, govern in a manner acceptable to at least some of the opposition parties. Even if the prime minister leads a majority government, he must still govern within (perhaps unwritten) constraints as determined by the members of his party—a premier in this situation is often at greater risk of losing his party leadership than his party is at risk of losing the next election. On the other hand, once elected a president can not only marginalize the influence of other parties, but can exclude rival factions in his own party as well, or even leave the party whose ticket he was elected under. The president can thus rule without any allies for the duration of one or possibly multiple terms, a worrisome situation for many interest groups. Juan Linz argues that:

The danger that zero-sum presidential elections pose is compounded by the rigidity of the president's fixed term in office. Winners and losers are sharply defined for the entire period of the presidential mandate... losers must wait four or five years without any access to executive power and patronage. The zero-sum game in presidential regimes raises the stakes of presidential elections and inevitably exacerbates their attendant tension and polarization.

Constitutions that only require plurality support are said to be especially undesirable, as significant power can be vested in a person who does not enjoy support from a majority of the population.

Some political scientists go further, and argue that presidential systems have difficulty sustaining democratic practices, noting that presidentialism has slipped into authoritarianism in many of the countries in which it has been implemented. Seymour Martin Lipset and others are careful to point out that this has taken place in political cultures not conducive to democracy, and that militaries have tended to play a prominent role in most of these countries. Nevertheless, certain aspects of the presidential system may have played a role in some situations.

In a presidential system, the legislature and the president have equally valid mandates from the public. There is often no way to reconcile conflict between the branches of government. When president and legislature are in disagreement and government is not working effectively, there is a powerful incentive to employ extra-constitutional maneuvres to break the deadlock.

Ecuador is sometimes presented as a case study of democratic failures over the past quarter-century. Presidents have ignored the legislature or bypassed it altogether. One president had the National Assembly teargassed, while another was kidnapped by paratroopers until he agreed to certain congressional demands. From 1979 through 1988, Ecuador staggered through a succession of executive-legislative confrontations that created a near permanent crisis atmosphere in the policy. In 1984, President León Febres Cordero tried to physically bar new Congressionally-appointed supreme court appointees from taking their seats. In Brazil, presidents have accomplished their objectives by creating executive agencies over which Congress had no say.

Separation of powers

Presidential systems are said by critics not to offer voters the kind of accountability seen in parliamentary systems. It is easy for either the president or Congress to escape blame by blaming the other. Describing the United States, former Treasury Secretary C. Douglas Dillon said "the president blames Congress, the Congress blames the president, and the public remains confused and disgusted with government in Washington".

In Congressional Government, Woodrow Wilson asked,

...how is the schoolmaster, the nation, to know which boy needs the whipping? ... Power and strict accountability for its use are the essential constituents of good government. ... It is, therefore, manifestly a radical defect in our federal system that it parcels out power and confuses responsibility as it does. The main purpose of the Convention of 1787 seems to have been to accomplish this grievous mistake. The 'literary theory' of checks and balances is simply a consistent account of what our constitution makers tried to do; and those checks and balances have proved mischievous just to the extent which they have succeeded in establishing themselves ... [the Framers] would be the first to admit that the only fruit of dividing power had been to make it irresponsible.

Consider the example of the increase in the federal debt of the United States that occurred during the presidency of Republican Ronald Reagan. Arguably, the deficits were the product of a bargain between President Reagan and the Democratic Speaker of the House of Representatives, Tip O'Neill - O'Neill agreed not to oppose tax cuts favored by Reagan, and in exchange Reagan agreed to sign budgets that failed to adequately restrain spending. In such a scenario, each side can claim to be displeased with the debt, plausibly blame the other side for the deficit, and still tout its own success.

Impediments to leadership change

Another alleged problem of presidentialism is that it is often difficult to remove a president from office early. Even if a president is "proved to be inefficient, even if he becomes unpopular, even if his policy is unacceptable to the majority of his countrymen, he and his methods must be endured until the moment comes for a new election." (Balfour, intro to the English Constitution). Consider John Tyler, who only became president because William Henry Harrison had died after thirty days. Tyler refused to sign Whig legislation, was loathed by his nominal party, but remained firmly in control of the executive branch. Since most presidential systems provide no legal means to remove a president simply for being unpopular, many presidential countries have experienced military coups to remove a leader who is said to have lost his mandate.

In parliamentary systems, unpopular leaders can be quickly removed by a vote of no confidence, a procedure which is reckoned to be a "pressure release valve" for political tension. Votes of no confidence are easier to achieve in minority government situations, but even if the unpopular leader heads a majority government, nonetheless he is often in a far less secure position than a president. Removing a president through impeachment is a procedure mandated by most constitutions, but impeachment proceedings usually cannot be initiated except in cases where the president has violated the constitution and/or broken the law. Impeachment is usually made into a very difficult process, by comparison the process of removing a party leader is governed by the (often much less formal) rules of the party in question. Nearly all parties (including governing parties) have a relatively simple and straightforward process for removing their leaders. If a premier sustains a serious enough blow to his/her popularity and refuses to resign on his/her own prior to the next election, then members of his/her party face the prospect of losing their seats. So other prominent party members have a very strong incentive to initiate a leadership challenge in hopes of mitigating damage to the party. More often than not, a premier facing a serious challenge will resolve to save face by resigning before he/she is formally removed—Margaret Thatcher's relinquishing of her premiership being a prominent, recent example.

In The English Constitution, Walter Bagehot criticized presidentialism because it does not allow a transfer in power in the event of an emergency.

Under a cabinet constitution at a sudden emergency the people can choose a ruler for the occasion. It is quite possible and even likely that he would not be ruler before the occasion. The great qualities, the imperious will, the rapid energy, the eager nature fit for a great crisis are not required—are impediments—in common times. A Lord Liverpool is better in everyday politics than a Chatham—a Louis Philippe far better than a Napoleon. By the structure of the world we want, at the sudden occurrence of a grave tempest, to change the helmsman—to replace the pilot of the calm by the pilot of the storm.

But under a presidential government you can do nothing of the kind. The American government calls itself a government of the supreme people; but at a quick crisis, the time when a sovereign power is most needed, you cannot find the supreme people. You have got a congress elected for one fixed period, going out perhaps by fixed installments, which cannot be accelerated or retarded—you have a president chosen for a fixed period, and immovable during that period: ..there is no elastic element... you have bespoken your government in advance, and whether it is what you want or not, by law you must keep it ... (The English Constitution, the Cabinet.)

Years later, Bagehot's observation came to life during World War II, when Neville Chamberlain was replaced with Winston Churchill.

Finally, many have criticized presidential systems for their alleged slowness in responding to their citizens' needs. Often, the checks and balances make action extremely difficult. Walter Bagehot said of the American system "the executive is crippled by not getting the law it needs, and the legislature is spoiled by having to act without responsibility: the executive becomes unfit for its name, since it cannot execute what it decides on; the legislature is demoralized by liberty, by taking decisions of others [and not itself] will suffer the effects". (ibid.)

Defenders of Presidential systems, on the other hand, hold that this can serve to ensure that minority wishes and rights are not trampled upon, thus preventing a "Tyranny of the majority" and vice versa protect the wishes and rights of the majority from abuse by legislature and/or executive that holds a contrary view point, especially when there are frequent, scheduled elections. It should be noted however, that despite the veto of President Wilson, Congress and the Senate still passed the National Prohibition Act which effectively outlawed the sale, manufacture, and transportation of alcohol.

British-Irish philosopher and MP Edmund Burke stated that officials should be elected based on "his [or her] unbiased opinion, his [or her] mature judgment, [and] his [or her] enlightened conscience", and therefore should reflect on the arguments for and against certain policies before taking positions and then act out on what an official would believe to be best in the long run for one's constituents and country as a whole even if it means short term backlash. Thus Defenders of Presidential systems hold that sometimes what is wisest may not always be the most popular decision and vice versa.