Updated

1:35 a.m. ET -- The Senate has voted to eliminate a tax break for a politically-connected conservative college in Michigan.

Democratic Sen. Jeff Merkley of Oregon proposed the amendment to eliminate the tax break for Hillsdale College in southern Michigan. He noted that Hillsdale has connections to powerful Republicans, including Education Secretary Betsy DeVos.

Merkley says, "Isn't that just the type of insider deal for the wealthy and well-connected that we should oppose?"

The Senate Republicans' sweeping tax package would impose a new tax on investment income earned by some private universities and colleges.

Republican Sen. Pat Toomey of Pennsylvania added a provision exempting certain colleges that don't receive federal funds. Democrats say Hillsdale was the only college that would benefit.

Merkley's amendment was adopted by a 52-48 vote.

1:20 a.m. ET -- The Senate has given a green light to opening Alaska's Arctic National Wildlife Refuge to oil drilling.

In a vote early Saturday morning, Republicans rejected an effort led by Democratic Sen. Maria Cantwell of Washington state to block drilling.

The vote was 52-48. Republican Sen. Lisa Murkowski of Alaska has pushed for oil and gas drilling in the refuge.

Opening the remote refuge to oil and gas drilling is a longtime Republican priority that most Democrats fiercely oppose.

The 19.6-million acre refuge in northeastern Alaska is one of the most pristine areas in the United States and is home to polar bears, caribou, migratory birds and other wildlife.

1:16 a.m. ET -- Word in the U.S. Capitol is that a vote on final passage of the tax reform bill may begin within 20-30 minutes. So final passage could happen by 2 a.m. ET or so.

12:26 a.m. ET -- There could be about five or six more votes tonight before the Senate gets to the final passage of the tax bill.

That should take at least an hour to an hour and a half, so long as votes on other amendments/motions aren’t required.

So at the earliest, we are looking at 1:45 to 2 a.m. ET before they start the final vote to finish the tax bill.

12:09 a.m. ET – Vice President Mike Pence quickly moved to the Senate chamber to preside over a vote on an amendment offered by U.S. Sen. Ted Cruz, R-Texas, about 529 savings plans.

The vote ended in a 50-50 tie, so in his capacity as president of the Senate, Pence cast a vote to break the tie.

Pence voted in the affirmative to make the vote 51-50 and the Senate agreed to the amendment.

The amendment would allow parents to use 529 college funds to pay private school tuition for students in kindergarten through high school.

Parents could also use the tax-exempt funds on home-schooling expenses.

All Senate Democrats opposed the measure. Sens. Susan Collins of Maine and Lisa Murkowski of Alaska were the only Republicans who voted against it.

Original story:

Vice President Mike Pence arrived at the U.S. Capitol late Friday as the U.S. Senate debated a tax-reform bill in hopes of getting a finalized proposal to a vote early Saturday.

If any votes are tied, then Pence – in the VP’s role as president of the Senate – would cast the deciding vote. An unspecified number of prelimary votes could be held before the final vote on the full bill.

No Democrats were expected to vote in favor of the tax bill, meaning Republicans need to convince skeptical members of the party to support the tax proposal in order to ensure passage.

One Democrat from a battleground state – who faces a challenging re-election next year – told Fox News it’s likely that Senate Majority Leader Mitch McConnell, R-Ky., intentionally crafted the bill to make it “impossible” for any Democrat -- even a moderate -- to vote yes.

That way, Republicans can use this weekend’s roll call vote on the tax bill against vulnerable Democrats in next year’s midterm elections.

Fox News’ Chad Pergram, Jason Donner and Joe DeFrank and the Associated Press contributed to this story.