Schumer: Trump 'the only person' blocking immigration deal
Senators march through grueling budget 'vote-a-rama'
The Senate is marching toward approval of the Republican budget by speeding through dozens of amendments in a "vote-a-rama" expected to end early Friday morning.
Republican leaders are expressing confidence that their blueprint will be approved, though they have a tight margin. The GOP can only afford to lose three Republican votes and pass its budget.
Senate Majority Whip John Cornyn (R-Texas) said he didn't believe there would be many defections.
"No, I think in the end, I think we'll do what the House did yesterday, which I think is very important for us to accomplish. I'm optimistic," he told The Hill.
The House GOP budget was approved by the lower chamber on Wednesday. If the Senate GOP pushes its budget across the finish line, Republicans in both chambers will seek to reconcile the two documents after a two-week recess that begins Friday.
Thursday's votes have put a spotlight on Sen. Ted Cruz (R-Texas) and three other Republicans expected to join him in the race for the White House: Sens. Rand Paul (Ky.), Marco Rubio (Fla.) and Lindsey Graham (S.C.).
Observers have seen Cruz and Paul as likely "no" votes on the budget.
Cruz, who launched his White House bid on Monday, told reporters Thursday that he was still evaluating the budget.
"I'm still assessing it. I'm looking at it carefully and I'll make a decision by the time the vote comes up," he said.
Sen. Mike Lee (R-Utah), another possible "no" vote, also refused to reveal his decision. Asked how he planned to vote, he told The Hill: "I'm kind of in the middle of something."
Graham and Rubio are expected to back the budget.
Graham is a member of the Senate Budget Committee and championed an amendment added in committee last week that boosted the Pentagon's war fund next year to $96 billion. Graham and others hope that funding will give the Pentagon more flexibility as it runs into a ceiling on its spending.
Paul and Rubio both offered amendments Thursday to raise spending for the Pentagon, each of which failed.
Paul's measure would have raised defense spending by nearly $190 billion over the next two years, but failed miserably and won only four "yes" votes. Ninety-six senators voted against it.
Rubio and freshman Sen. Tom Cotton (R-Ark.) also offered an amendment to boost defense spending. It fared better than Paul's effort, but was also defeated in a 32-68 vote to overcome a point of order.
Cruz and Paul were split on Rubio's proposal, which would have given the Defense Department more money by raising its spending to the levels proposed by former Defense Secretary Robert Gates in 2012. Cruz supported Rubio's measure, while Paul voted against it.
Another difference between the two approaches was that Rubio's additional defense spending was not offset with spending cuts to other parts of the government. Paul's increased defense spending was offset with cuts to other programs.
Other amendments in the vote-a-rama, which began at noon, have dealt with ObamaCare, the Guant namo Bay prison, education, paid leave and taxes, among other issues.
Divisions among Democrats have been notable in some of the votes, including on an amendment that would require ObamaCare insurance billings to note an ObamaCare tax.
Democratic Sens. Joe Manchin (W.Va.) and Michael Bennet (Colo.) both voted with Republicans to approve that measure, which GOP sponsor Sen. Tim Scott (R-S.C.) said was meant to increase awareness about the healthcare tax paid by people who sign up for plans under ObamaCare.
Manchin is from a reliably Republican state in presidential contests, while Bennet is up for reelection in 2016.
Democratic Sens. Joe Donnelly (Ind.), Heidi Heitkamp (N.D.), Claire McCaskill (Mo.) and Manchin voted in favor of an amendment from Sen. Roy Blunt (R-Mo.) intended to block a federal tax on carbon emissions.
Several amendments backed by Democrats were also approved, including one from Sen. Patty Murray (D-Wash.) that would encourage employers to offer up to seven paid sick days.
The vote could have consequences for the 2016 election, where Democrats are planning to make paid sick leave a big issue.
Rubio, Paul and Cruz voted against the amendment, but GOP Sens. Kelly Ayotte (N.H.), John Hoeven (N.D.), Johnny Isakson (Ga.), Mark Kirk (Ill.), John McCain (Ariz.), Lisa Murkowski (Alaska), Rob Portman (Ohio) and John Thune (S.D.), all of whom are up for reelection in 2016, backed it.
Once Republicans approve their budget, the real difficult work of reconciling the House and Senate versions will begin.
The last time a Republican-controlled Congress approved a joint conference agreement was in 2005.
If a joint conference agreement does pass both chambers, Republicans will be able to trigger a budget procedure known as reconciliation that could be used to target ObamaCare, reform the tax code and raise the debt ceiling, among other things. Bills written under reconciliation rules could not be blocked by a Senate filibuster.
Republicans in both chambers hope to strike that joint agreement by April 15.
The grueling day in the Senate is also providing some lighter moments.
Sen. Bill Cassidy (R-La.), while presiding on Thursday afternoon, told Sen. Barbara Boxer (D-Calif.), who was trying to find out how long a vote had been open, that there wouldn't be anymore "parliamentary inquiries" during roll-call votes. "The parliamentary inquiry is ... the sufferance of the Senate," he said.
Boxer shot back: "Well the Senate is definitely suffering."