A marathon voting session on President Donald Trump’s sweeping domestic policy bill is underway in the Senate and has stretched overnight into the early hours of Tuesday morning after a weekend of negotiations and delays.

The vote-a-rama – an open-ended series of votes on amendments, some political, some substantive – started around 9:35 a.m. on Monday and is still going. The extended voting session provides an opportunity for Republicans to make any eleventh-hour adjustments to the package and Democrats to push on GOP weak points in the bill and put their colleagues on the spot. Those politically tough votes are likely to provide fodder for campaign ads down the line.

Senate Majority Leader John Thune told reporters around 4:30 a.m. “we’re close,” saying they still have “a few amendment votes” until final passage. But Thune did not give a number for how many amendment votes are left and it’s unclear how long the process will take with no final vote yet scheduled.

Trump’s multitrillion-dollar bill would lower federal taxes and infuse more money into the Pentagon and border security agencies, while downsizing government safety-net programs including Medicaid.

Democrats have zeroed in on Medicaid and other safety-net programs, such as food stamps, as they message against the president’s agenda. The vote-a-rama comes after Senate Democrats employed a major delay tactic over the weekend that forced clerks to spend more than a dozen hours reading aloud the entire bill.

Lawmakers are up against an extremely tight timeline to pass the legislation. The president has demanded Congress deliver the bill to his desk by the Fourth of July, but the measure must still go back to the House if it passes the Senate.