Republican Sen. James Lankford, who spent months negotiating the border provisions the GOP demanded, said he may vote against his own bill this week.

Senate Republicans on Monday signaled their plan to filibuster bipartisan legislation that paired tougher border policy with more U.S. aid to Ukraine, a stunning reversal less than 24 hours after the legislation had been unveiled.

With ex-president Donald Trump urging them to kill it, and many on the right up in arms about the proposal, top Senate Republicans emerged from a heated closed-door meeting and said they needed more time to review the agreement, suggesting that a scheduled Wednesday vote to advance the bill is all but doomed to fail.