Labour's Barry Gardiner during an appearance on Question Time.
The prime minister had cancelled a vote on her deal last month at the last minute to avoid a humiliating defeat. The Labour Party leader could be seen appearing to mouth the words in response to May making a joke about his failure to demand a no-confidence vote against her government after he had accused her of leading the country "into a national crisis".
A Labour spokesperson said: "If the government is defeated next week, it will clearly have lost the confidence of parliament and there should be a general election".
The Britain is due to leave the European Union on March 29, but the British Prime Minister Theresa May is struggling very hard to get her Brexit deal passed through the parliament with opening huge uncertainty over whether the deal could be possible or not, or even whether the country will vote to leave at all.
The move comes ahead of a meeting of the Labour Party's International Policy Commission on Wednesday, which is set to discuss Brexit.
But the Labour leader will describe an election as "not only the most practical option, it is also the most democratic option".
In his speech in Wakefield to an audience of workers and party members, the Labour leader will say: "If the Government can not pass its most important legislation, then there must be a general election at the earliest opportunity".
A spokesman for May said the government would consider amendments as it usually does, but it was important that ministers were able to deliver Brexit, including in a no-deal scenario.
Jeremy Corbyn has come under pressure to back Labour's own referendum on a potential Brexit deal should there be a general election.
The visit has prompted speculation Mr Abe has been flown in to bolster global support for the prime minister's Brexit agreement.
MPs will continue their debate on Mrs May's agreement on Thursday, prior to Tuesday's scheduled vote.