* No clear frontunner in race to succeed Boris Johnson
* Ex-finance minister Sunak won first 2 lawmaker votes
* 'Knives out' for bookies' favourite Mordaunt
* First TV debate to be held on Friday
By Michael Holden
LONDON, July 15 (Reuters) - The five remaining contenders to be Britain's next prime minister will go head to head in the first of three televised debates on Friday, hoping a good performance will boost their chances in a battle that so far has no clear frontrunner.
An initial field of 11 challengers has been whittled down following two days of votes by lawmakers from the ruling Conservative Party, but no individual has yet emerged as the obvious successor to Boris Johnson who announced he was stepping down following a series of scandals.
While ex-finance minister Rishi Sunak has topped those two votes, he faces stiff competition from foreign minister Liz Truss, who has the backing of a number of senior figures, and junior trade minister Penny Mordaunt, who polls suggest is the most popular with party members who will decide the winner.
Former equalities minister Kemi Badenoch and Tom Tugendhat, chair of parliament's Foreign Affairs Committee, also remain in the running and will hope that a strong showing in the televised debates will inject momentum into their campaigns.
Whoever gets the job will take on rocketing inflation and low economic growth, as well as the public's lack of confidence in politics after Johnson's scandal-ridden time in power.
Voter polls also suggest the Conservatives are falling significantly behind the opposition Labour Party.
"Who's going to be the best person to take on (Labour leader) Keir Starmer at the next general election?," lawmaker Richard Holden, a Sunak supporter, told Sky News.
"That's what I'm interested in because I need to hold my seat in order to deliver for the people in my seat."
DOWN TO TWO BY JULY 21
Sunak, whose decision to quit the Treasury last week helped trigger a cascade of ministerial resignations that brought down Johnson, remains the favourite among his 358 Conservative parliamentary colleagues.
But his lead over Truss and Mordaunt is slim, and both could overtake him depending on whom lawmakers who backed other candidates choose to support.
On Thursday, Attorney General Suella Braverman was knocked out of the race and she has thrown her support behind Truss, who has also gained the backing from David Frost who negotiated Britain's exit from the European Union.
The Times newspaper reported that Johnson was urging defeated leadership candidates to back "anyone but Rishi".