LONDON (REUTERS) - British Prime Minister Theresa May declined to comment on Monday (June 5) on how many extra seats in parliament she would need to win in order to have been justified in calling an early election.

May's gamble on a June 8 vote, aimed at strengthening her hand in upcoming Brexit negotiations, has been thrust into doubt since opinion polls have shown her Conservative Party's lead shortening markedly in recent weeks.

The Conservatives held a 17-seat working majority before the election.

Some polls have predicted she could win the most seats at the election, but without a majority.

"Throughout my many years in politics I have always been very clear, I never set expectations of that sort and I never predict election results," May said, when asked by Reuters how many seats she would need to win to justify her decision.