London   - Rebels in Prime Minister Theresa May's ruling Conservative party have urged her to amend a parliamentary bill to allow a "meaningful vote" on the terms of Brexit. The rebels, led by former attorney general Dominic Grieve, have tabled an amendment to the EU (Withdrawal) Bill to "require the final deal with the EU to be approved by statute passed by parliament."

More pressure on Theresa May

A vote on the amendment is expected late Wednesday unless May's government reaches a compromise with the group, who claim they have enough cross-party support to win a vote against May's minority government, which relies on 10 lawmakers from Northern Ireland's Democratic Unionist Party in key votes. Labour, the largest opposition party, will back the amendment if it goes to a vote, said shadow Brexit secretary Keir Starmer. "Labour will back Dominic Grieve's amendment giving parliament a proper say on the Brexit deal if he pushes it to a vote tonight," Starmer said on Twitter. "The terms of our future are not for the government alone to determine," he said.

Attempts to amend the law

Liberal Democrat Brexit spokesman Tom Brake, Green Party co-leader Caroline Lucas, Labour's Chuka Umunna and Scottish National Party lawmaker Stephen Gethins led a rally of the pro-EU group Open Britain near parliament early Wednesday to support the amendment to "put sovereignty at the heart of the bill." In a bid to placate the rebels, Brexit Secretary David Davis has reportedly written to Conservative lawmakers to promise several votes on the final Brexit deal. But Grieve told the BBC he will still push the amendment unless the government shows "greater felxibility."