Two major political figures announced they planned to step down last night, a week after the local election results.
Labour frontbencher Peter Hain, who has been in a lead role for the party since the start of the New Labour project, is to stand down from the shadow Cabinet. Green leader Caroline Lucas announced she will not seek re-election when her term ends in September.
Mr Hain's decision has sparked rumours about a possible reshuffle on the Labour front bench.
But the shadow Welsh secretary insisted he had told leader Ed Miliband of his intention to stand down at Christmas and kept it secret to see through the local elections in Wales, where he chaired Labour's campaign.
"We got our best results for a long, long time so I thought this was the right time to do it," he told BBC Radio Wales.
"[Mr Miliband] was disappointed but Ed is now well into his stride. He's gaining support, his stock is rising in the public mind, people have got to know him better."
The South African anti-apartheid campaigner moved to the UK as a teenager and entered the Commons in 1991. He served under Tony Blair and Gordon Brown's Cabinet as Welsh secretary, leader of the Commons, Northern Ireland secretary and work and pensions secretary, among other roles.
Mr Miliband said: "Peter Hain has made an enormous contribution from the front bench over the past 16 years.
"He has been an exceptional colleague and trusted friend both in government and in opposition. He will be a great loss to the shadow Cabinet."
He will continue to serve as an MP, as will Ms Lucas, who became the first Green MP in 2010 when she took the Brighton Pavilion seat.
Ms Lucas said she wanted the leadership role to be used to spotlight rising political stars in the party while she got stuck into the "frontline" work of being an MP.
"I'm proud that during the four years of my term, we've moved Green politics forward to a higher level, with the party by far the most influential it has ever been," she said.
Jenny Jones, who recently beat Liberal Democrat candidate Brian Paddick to third place in the London mayoral election, has already ruled herself out the race.
The Green party has steadily increased its influence under Ms Lucas, who was elected when it scrapped the previous system of a gender-balanced two-person leadership.
But the formation of the coalition could raise issues for the party at the general election, with some analysts expecting the left-wing vote to consolidate around Labour in response to the cuts.