20th July 2026
UK and the US have fundamentally different constitutional systems.
The UK: Government depends on Parliament
The UK uses a parliamentary system.
Voters elect Members of Parliament (MPs), not the Prime Minister directly.
The Prime Minister is simply the person who can command a majority in the House of Commons.
If that majority changes, the Prime Minister can change almost immediately.
For example:
If the governing party replaces its leader (as happened when Boris Johnson was replaced by Liz Truss, and then by Rishi Sunak), there is no need for a general election.
If a government loses a vote of confidence, another government can be formed within days if someone else has majority support.
The King plays only a constitutional role by appointing the person most likely to command that majority.
The USA: Fixed presidential terms
The United States has a presidential system.
Americans vote separately for Congress and for the President.
The President serves a fixed four-year term.
Congress cannot simply vote the President out because they disagree with his policies.
The President can only leave office early if:
they resign (like Richard Nixon),
die,
become incapacitated under the 25th Amendment, or
are removed through impeachment and conviction.
Why impeachment takes so long
Impeachment is deliberately difficult.
It requires:
The House of Representatives to approve articles of impeachment by a simple majority.
A trial in the Senate.
A two-thirds majority in the Senate to convict and remove the President.
That high threshold was designed by the Founding Fathers to stop governments changing because of temporary political disagreements.
Why the systems were designed differently
The UK's constitution evolved over many centuries. Parliament gradually became more powerful than the monarch, and governments became responsible to Parliament.
The US Constitution was written in 1787 after independence from Britain. The framers wanted to prevent:
dictatorship,
monarch-like presidents,
governments collapsing every few months.
They deliberately separated power between:
the President,
Congress,
and the Supreme Court.
This creates checks and balances but also makes change slower.
The trade-off
UK system
✅ Governments can change quickly.
✅ Easier to respond to political crises.
❌ A Prime Minister can change without a general election.
❌ Governments can sometimes fall frequently if they lose parliamentary support.
US system
✅ Stability with fixed terms.
✅ Presidents cannot easily be removed for political reasons.
❌ Even if a President becomes very unpopular, they usually remain in office until the next election unless removed through the difficult impeachment process.
❌ Deadlock is common when Congress and the President are controlled by different parties.
An interesting comparison
The UK can replace a Prime Minister in a matter of days, because the key question is simply: Who commands a majority in Parliament?
In the United States, replacing a President before the end of a term was intentionally made exceptionally difficult, because the Constitution was designed to make the office independent of Congress and resistant to short-term political pressure.
This constitutional difference explains why British politics can sometimes appear fast-moving and unstable, while American politics can seem slow and locked in place even during periods of intense political conflict.