Theresa May will not find it “plain sailing” as she rushes to have her Brexit bill approved by March 7, a senior Tory has warned.

Lords were told that the Prime Minister’s timetable shows she wishes legislation permitting her to trigger Article 50 to have passed all stages by the first Tuesday in March.

It would allow Ms May to use a European Council summit two days later to officially launch the Brexit process, though she could wait longer if she wished.

With the debate on the Bill to trigger Article 50 starting on Tuesday, a senior Tory figure told The Independent: “What we are seeing now is a huge raft of amendments being tabled.

“There are cross party talks going on about this. It’s not going to be plain sailing for the Prime Minster.”

The Bill is eventually likely to pass without amendment, with Tory rebels in the Commons appearing to back away from trouble as long as Ms May produces a promised White Paper on her negotiating Strategy soon.

There is some chance for delay in the Lords, with amendments potentially debated including ones seeking a guarantee for EU citizens rights, a vote on leaving the single market, on having a second referendum and on the terms of the final vote in Parliament on Ms May’s deal, which is likely in two years.

Theresa May pledges white paper on Brexit strategy

Brexit Secretary David Davis is expected to say at the start of the debate: “It is not a Bill about whether or not the UK should leave the EU, or how it should do so.

“It is simply about implementing a decision already made, a point of no return already passed. We asked the people of the UK if they wanted to leave the EU, they decided they did.”