Two senior UK lawmakers on Friday became the latest from the ruling Conservatives to announce that they will stand down at the next election, as Rishi Sunak's party appears headed for defeat.

Armed Forces minister James Heappey said he had taken the "painful decision" not to fight his seat at the nationwide vote, which is expected to occur in the second half of this year.

His announcement came after Brandon Lewis, a former chairman of the Tories who was also Northern Ireland and justice secretary, said late Thursday he would not be a candidate.

At least 66 Conservatives and former Conservatives have now announced they are leaving parliament at the election -- the most since Labour's landslide win under Tony Blair in 1997.

The most high-profile of them is former prime minister Theresa May, who revealed last week that she would step down after 27 years as an MP.

The retirements add to a growing feeling in Westminster that the election will see the Tories kicked out of government after 14 years in power.

The Conservatives have consistently trailed the main Labour opposition, led by Keir Starmer, in national surveys since October 2022.

Numerous resets by Sunak have so far failed to claw back support, although the polls are expected to narrow as polling day gets nearer.

Labour also require a record vote swing to win an overall majority in the House of Commons, meaning the result is far from a foregone conclusion.

The Times newspaper reported that Heappey, 43, is due to resign his ministerial role at the end of the month due to unhappiness over levels of government spending on defence.

He said in his statement that he was quitting as an MP to put his family first "and pursue a different career", and would continue to support Sunak until he stands down.

Almost 100 of parliament's 650 MPs have said they will not seek re-election.

Sunak on Thursday ruled out calling the election on May 2 to coincide with local polls.

The premier could wait as late as January 2025 to go to the country but has said his "working assumption" is the vote will be in the second half of the year.