Boris Johnson has promised to scrap the Fixed Term Parliaments Act (FTPA), the law which prevents prime ministers calling general elections whenever they like.
The law, introduced the the Conservative-Lib Dem coalition, frustrated three attempts by Johnson to call an election on his own terms as it requires two-thirds of MPs to vote for a poll.
In the end MPs backed an election on December 12 by passing a short piece of legislation that fixed that date for the vote.
The Tory manifesto published on Sunday pledged to “get rid” of the FTPA as it has “led to paralysis at a time the country needed decisive action”.
Jeremy Corbyn’s Labour manifesto has also said it would abolish the law as it “stifled democracy and propped up weak governments”.
If the FTPA is axed, Johnson or Corbyn will have have the power to call an election whenever they like.
Critics of the FTPA when it was introduced said it was a one-off fix to ensure the coalition did not collapse.
But its advocates argued it the power to call an election should rest with parliament not the PM alone.
The Lib Dems have not proposed ditched the legislation.
Under the terms of the FTPA general elections are supposed to be held in the summer every five years. If it is not repealed by the next government, the next election will be set for May 2024.
Other constitutional measures in the Tory manifesto include a commitment to redraw the electoral map to equalise the number of people in each constituency.
The Conservatives will also press ahead with controversial plans to introduce an ID requirement to vote. Critics have argued it risks disenfranchising swathes of voters.
British citizens living overseas will be able to vote in elections beyond the current 15-year limit.
The Tories will keep the First Past The Post system for general elections, as well as resist pressure to lower the voting age to 16.