Jeremy Corbyn was applauded by Labour MPs as he returned to the House of Commons following his party’s surprise election gains.
The Labour leader arrived in the chamber as MPs met to choose the Speaker for the new Parliament.
The reaction by Labour MPs is in stark contrast to the tribulations being endured by Theresa May, who is scrabbling to secure a deal with the DUP to enable her to form a minority Conservative Government.
Arlene Foster, the Democratic Unionist Party leader, has said a deal could be completed “soon” and that discussions with the Prime Minister were “going well”.
She said she hoped for a “successful conclusion”.
But on Tuesday, Sir John Major became the latest senior figure to say he was concerned about the impact the deal could have on the Northern Ireland peace process.
The former prime minister, who began work engaging with the IRA to end the Northern Ireland conflict, said the peace process was still “fragile” and cautioned the pact could mean the Government will no longer be seen as impartial.
He told BBC Radio 4’s World At One Programme: “People regard the peace process which was very hard earned over very many years by a lot of people, people shouldn’t regard it as a given, it isn’t certain, it is under stress, it is fragile.
“Although I don’t expect it suddenly to collapse, because there’s a broad consensus that wishes it to continue, I think we have to take care with it and take care that everything we do does not exaggerate the underlying differences that still are there in the Northern Ireland community.”
He said he was “concerned” about the deal between the two parties, and saying he was “wary” and “dubious” about it “both for peace process reasons but also for others reasons as well”.
Over the weekend, Mrs May was warned by former Chancellor George Osborne she was a “dead woman walking“.
The former Northern Ireland Secretary Shaun Woodward also described the PM’s actions as “morally reprehensible“.
Mr Corbyn is expected to make a short speech should Buckingham MP John Bercow be returned to the role.
Labour secured 262 MPs at the June 8 General Election, up from the 232 elected in 2015 while Ed Miliband was leader.
The Conservatives remain the largest party but Mr Corbyn’s party are feeling buoyant after their vote share soared.