Two more US Republican senators announced their opposition Monday to their party’s efforts to revamp Obamacare, derailing the controversial legislation in its current form and potentially dealing a monumental setback to President Donald Trump, reports AFP from Washington.

Republican leaders are desperate for a major legislative victory this year—and keen to fulfill Trump’s campaign pledge to dismantle the 2010 health care reforms of his predecessor Barack Obama, formally called the Affordable Care Act.

But they had no votes to spare.

Republicans control 52 of the chamber’s 100 seats. Democrats are united against the controversial legislation, while Republicans Susan Collins and Rand Paul declared their opposition last week.

So when Senate conservatives Mike Lee and Jerry Moran announced late Monday they could not support the bill, the news sent shockwaves across Washington.

“We should not put our stamp of approval on bad policy,” Moran—who faced considerable opposition at home in Kansas to the measure—said in a statement, adding that the new bill “fails to repeal the Affordable Care Act or address health care’s rising costs.”

For Lee, “in addition to not repealing all of the Obamacare taxes, it doesn’t go far enough in lowering premiums for middle class families; nor does it create enough free space from the most costly Obamacare regulations.”

Their defections mean that the bill has no chance of even getting a vote on the Senate floor unless Senate Majority Leader Mitch McConnell decides to make significant changes to woo skeptics back into the fold.

“Republicans should just REPEAL failing ObamaCare now & work on a new Healthcare Plan that will start from a clean slate. Dems will join in!” Trump tweeted after Lee and Moran made their opposition known. In a statement McConnell acknowledged “regretfully” that his effort had failed. But he wasn’t giving up.

“So, in the coming days, the Senate will vote to take up ... a repeal of Obamacare with a two-year delay to provide for a stable transition period,” he said, without setting a date.