WASHINGTON (AP) — The Senate voted on Tuesday to launch a new effort to reopen the Department of Homeland Security and end the longest partial government shutdown in history.

Watch the Senate floor live in the video player above.

The 52-46 vote was the first step in a budget process that Republicans hope will unlock the funding for Immigration and Customs Enforcement and Border Patrol. Senate Democrats have blocked money for those agencies since mid-February, demanding policy changes after the fatal shootings of two protesters by federal agents.

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Republicans are now trying to fund the two agencies through a complicated, time-consuming process called budget reconciliation, a maneuver that they also used to pass President Donald Trump's package of tax and spending cuts last year with no Democratic votes. The Senate has already voted on a bipartisan basis to reopen the rest of the department, but Republican leaders in the House say they won't take that bill up until the Senate shows progress toward funding ICE and Border Patrol, as well.

The budget process only requires a simple majority in the Senate, bypassing filibuster rules that require Republicans to find 60 votes on most bills when they only hold 53 seats. But it also comes with increased scrutiny from the Senate parliamentarian and an open-ended series of amendment votes that could potentially alter the bill.

"It's not my preference, but it is reality," Thune said.

Senate Minority Leader Chuck Schumer, D-N.Y., called the budget workaround a "partisan sideshow" and said the resolution will pour money into immigration enforcement "without putting any restraints on these rogue agencies' rampant violence in our streets."

Senate leaders try to keep bill focused on ICE, border patrol

The Senate Budget Committee on Tuesday released the estimated $70 billion resolution to fund ICE and Border Patrol for three years, through the rest of Trump's term. Thune and other GOP leaders say they hope to keep the bill narrowly focused and pass it by the end of the month.

But that could prove difficult as many in the party see it as the last real chance this year to enact their priorities. Republicans in both the Senate and House have pushed to add other items, including money for farmers and Trump's proof of citizenship voting bill, called the SAVE America Act.

Republican leaders say they would try to do a second partisan budget reconciliation bill to deal with some of those issues. But many of their colleagues are skeptical, especially with thin GOP margins in both chambers of Congress and an election approaching.

Senators who have been pushing for more to be included in the original resolution say they are preparing amendments to try and add them on the Senate floor. Sen. John Kennedy, R-La., said he'll try to add parts of the SAVE America Act and proposals related to the economy.

"A lot of Americans are very worried about the cost of living and we need to address it," Kennedy said Monday.

But at a lunch meeting on Tuesday, Republican senators were mostly united around Thune's plan.

"I think people recognize that we have to act quickly," said Sen. Ron Johnson, R-Wis. "The more you add the more that slows the process down."

Democrats say reforms still needed at ICE

Democrats say any funding bill should place restraints on federal immigration authorities, including better identification for federal officers and more use of judicial warrants, among other asks.

"After the killings of Renee Good and Alex Pretti, people across the country demanded ICE be reined in," said Washington Sen. Patty Murray, the top Democrat on the Senate Appropriations Committee. "But instead of working with Democrats to enact real reform, Republicans rejected the most basic accountability measures, and now they're rushing to give ICE billions of dollars more."

After federal agents shot Renee Good and Alex Pretti in Minneapolis in January, Trump agreed to a Democratic request that the Homeland Security bill be separated from a larger spending measure that became law. But bipartisan negotiations went nowhere, and the DHS funding lapsed with no agreement on changes to the Trump administration's immigration enforcement tactics.

In March, the Senate passed legislation by voice vote that would separate out ICE and Border Patrol and fund the rest of the department, including the Transportation Security Administration as security lines grew long at some airports. But Republicans in the House refused to vote for it, saying they wouldn't support any bill that didn't include money for immigration enforcement.

Congress then left town for a two-week recess, leaving the issue unresolved. Trump has used executive orders to pay some department salaries in the meantime, but the future of those paychecks is uncertain.

During the recess, Thune and House Speaker Mike Johnson announced that they would pursue a two-track approach — pass the Senate bill that includes most of the department's funding through regular order and use the party-line bill to pass ICE and CBP funding.

Weeks later, though, Johnson has still not said when the House will take up the Senate's legislation funding the rest of the department. And it is unclear if members of his GOP conference will unite behind the narrowed budget bill.

"We'll figure this out," Johnson said ahead of the Senate vote on Tuesday. "We've got lots of discussion today and in the coming days to make sure we can get that through and I think we will."

Associated Press writers Steven Sloan and Kevin Freking contributed to this report.