The Senate voted to block President Donald Trump’s emergency declaration to build his long-promised border wall, with 12 GOP Senators voting with all 47 Democrats in rebuking the president in a fight over constitutional authority vs. border security.

The question before the vote was not whether the declaration would be blocked, but exactly how many Republicans would side with the Democrats, who only needed four from the GOP side of the aisle.

Trump said before the vote he will “probably” veto the resolution, his first as president.

“I don’t know what the vote will be. It doesn’t matter,” he said. “I will probably have to veto.”

After the vote he made his intentions even more clear.

Republican senators say they are worried about presidential overreach when it comes to appropriating taxpayer funds, for which Congress is granted sole authority by the Constitution.

Republicans who voted against emergency declaration include: Mitt Romney and Mike Lee of Utah, Susan Collins of Maine, Lisa Murkowski of Alaska, Rand Paul of Kentucky, Rob Portman of Ohio, Marco Rubio of Florida, Jerry Moran of Kansas, Roger Wicker of Mississippi, Pat Toomey of Rhode Island, Roy Blunt of Missouri and Lamar Alexander of Tennessee.

In a last-minute reversal, Thom Tillis of North Carolina changed his mind and voted for the declaration.

Georgia’s Johnny Isakson voted for Trump’s declaration, saying “I’m voting for border security,” after deciding to do so late last night, but he also lamented the growing dysfunction in our nation’s capital.

“The national emergency right now is that Washington is in a mess,” he said.

The Democrat-controlled House overwhelmingly voted in favor of a resolution blocking the emergency declaration, 245-182, on Feb. 26.

California and at least 15 other states have already filed suit, and the case is most likely to end up before the Supreme Court, where Paul said it will likely be deemed unconstitutional. Paul also said Trump’s own two appointments, Neil Gorsuch and Brett Kavanaugh, will vote against him.

Per Rand Paul’s op-ed, via Fox News:

With regard to the Constitution, the Supreme Court made it very clear in Youngstown Steel in 1952, in a case that is being closely reexamined in the discussion of executive power.  In Youngstown, the Court ruled that there are three kinds of executive order: orders that carry out an expressly voiced congressional position, orders where Congress’ will is unclear, and, finally, orders clearly opposed to the will of Congress.

To my mind, like it or not, we had this conversation.  In fact, the government was shut down in a public battle over how much money would be spent on the wall and border security.  It ended with a deal that Congress passed and the president signed into law, thus determining the amount.

Congress clearly expressed its will not to spend more than $1.3 billion and to restrict how much of that money could go to barriers.  Therefore, President Trump’s emergency order is clearly in opposition to the will of Congress.

It was the second rebuke of Trump’s authority in as many days after the Senate passed a measure Wednesday night rejecting U.S. military support for the Saudi-led military campaign in Yemen.

Per Bloomberg:

The reprimands — both requiring defections from Republican ranks — come as Trump seeks to consolidate the party’s support ahead of what promises to be a tough fight for re-election in 2020. They also underscore the consequences of a midterm election that left Democrats in control of the House and GOP lawmakers unable to shield the president from legislation he opposed.

While Republicans in Congress have occasionally criticized the administration, the two measures this week mark the first instances in which party leaders haven’t been able to stop bills that embarrass Trump.

The Yemen legislation, which is likely to pass the House in coming weeks, picked up support beginning late last year when Trump defended Saudi Arabia after columnist Jamal Khashoggi was killed in the Saudi consulate in Istanbul.

Trump was able to avoid a full-scale rebellion by GOP lawmakers that would allow a veto override. That means Trump — barring separate legal challenges — should be able to move forward both with his efforts to redirect funding to the construction of the border wall and arms sales to Saudi Arabia.

Maintaining that hold over his party will be crucial as Trump continues to engage in high-stakes negotiations with House Speaker Nancy Pelosi, who demonstrated during the recent 35-day government shutdown her ability to hold Democrats in line despite high political risk.

The vetoes offer a political stress test of Trump’s use of executive authority — an approach he employed when his party fully controlled Congress. That’s only expected to increase as the president is confronted with a divided government.

Minimizing public rebukes from his own party is especially important as Trump faces a 2020 campaign in which his Democratic challenger seems certain to paint his presidency as a model of ineffective governance by an extremist and novice. White House officials have adopted a dual-track approach to keep the this week’s votes from snowballing into a broader problem.