In an interview on Newsnight on Wednesday evening, the Leicester West MP told Evan Davis the party simply "didn't get the voters" at the election which was why it lost. "People didn’t trust us on the economy," she conceded.
"I think we were spending too much before the crash but we did not case the financial criss that was global and actually what really concerned people was we seemed to slow to face up to the challenge," she said.
Under Ed Miliband, she said, Labour had failed to convince voters it was able to "balance the books and live within our means".
Kendall, who is seen to be on the right of the party, was yesterday joined by Yvette Cooper and Andy Burnham in the race to succeed Miliband. Chuka Umunna has also declared his intention to run.
Cooper pledged to make life better for families while rejecting calls to rehash the formula for success developed by treble election winner Tony Blair.
In contrast Burnham signalled that he wanted to return the party to Mr Blair's approach of speaking for the whole country and appealing to people's aspiration
Umunna has set out ambitions to win back voters in the south east of England and return Labour to office within five years.
All the potential leaders will be honing their messages ahead of the first Parliamentary Labour Party hustings on June 8.
The long race for the leadership will end when ballots close on September 10, with the winner to be announced two days later at a special conference.