TORY MPs claim London mayor Boris Johnson would boost his credibility as a potential Conservative leader if he showed "political courage" by fighting the Clacton by-election.
Polls show Ukip is set to win the by-election on October 9, triggered by the defection of the former Tory MP Douglas Carswell.
The London mayor, who is vying for selection in Uxbridge, has brushed off suggestions he should put his name forward for the Clacton seat.
But in an article for the conservativehome website, Hendon MP Matthew Offord and John Stevenson, MP for Carlisle, wrote: "For Boris, this is an opportunity for him to step up to the plate, show his political courage, fight for the Conservative cause and clearly set out his willingness to play for the team.
"Were Boris to win, he would clearly have demonstrated his continuing ability to win difficult elections, as well as his ability to attract voters outside London."
They said a win by Mr Johnson would "de-rail the Farage bandwagon" as well as "steady the nerves" of several Conservative MPs.
Mr Johnson previously said he will not put his name forward for the Tory candidacy in Clacton.