London, Jul 12 (IANS): UK's former Chancellor of the Exchequer Rishi Sunak underlined his status as Tory leadership front runner on Tuesday as more Cabinet big beasts backed him - with Foreign Secretary Liz Truss begging the Tory right to unite behind her to take him on, media reports said on Tuesday.

Would-be PMs have just hours left to rack up the 20 nominations needed to feature in the first round of the contest, with voting due to start on Wednesday, Daily Mail reported.

Sunak already appears to be well over the threshold as he formally launched his campaign this morning, introduced by deputy PM Dominic Raab and Grant Shapps.

The former Chancellor again batted away calls for tax cuts before inflation is under control, saying "we need to have a grown up conversation". At the event in Westminster, he also heaped praise on Boris Johnson, describing him as "one of the most remarkable people I have ever met" who has a "good heart" - but it was "not working" any more.

Sunak - who only took a few questions from the media while journalists asking combative points were heckled by the crowd - said his plan was to "tackle inflation, grow the economy and cut taxes". "I want to have a grown up conversation where I can tell you the truth," he said.

Raab said before the speech: "We need a leader who can win... he is the only one who can win", Daily Mail reported.

Penny Mordaunt and Tom Tugendhat also seem to have reached nominations the mark, while Truss is over the top after securing endorsements from Boris Johnson allies Jacob Rees-Mogg and Nadine Dorries - who declared their loyalty on the steps of Downing Street.

However, other big names are struggling, with Jeremy Hunt, Nadhim Zahawi, Sajid Javid, and Priti Patel all short of declared backers.