The White House is reportedly appealing to Republican senators to stand with President Donald Trump on his controversial emergency declaration to get funds to build the U.S.-Mexico border wall, asking undecided lawmakers to back him in next week’s vote.

SEN. JOHN CORNYN: “If I voted to disapprove it, it would basically say I am not for what the president is trying to accomplish at the border — which I am for.”

Majority Leader Mitch McConnell said Monday the Senate has enough votes to block the president’s emergency declaration after four Republicans have announced they will vote with the Democrats, giving them the 51-vote simple majority needed.

The four GOP senators are Susan Collins of Maine, Lisa Murkowski of Alaska, Rand Paul of Kentucky and Thom Tillis of North Carolina. Though, Lamar Alexander, R-Tenn., and reportedly up to 10 more were ready to vote against it when Paul came forward Saturday.

Trump implored Republican Senators to stand with him in a tweet on Wednesday.

Per The Washington Post:

Yet many GOP senators weighing a vote on nullifying Trump’s national emergency are being confronted with a difficult choice: Buck their president and potentially draw the wrath of core Republican voters, or support Trump’s controversial declaration for a wall that remains unpopular with the broader public.

The potential consequences are more acute for GOP senators up for reelection next year, particularly those in Democratic-leaning or swing states who may need to create some distance from Trump yet could invite political challenges from the right should they vote for a disapproval resolution.

GOP senators who have come out against the emergency declaration say they don’t want to give too much power to the president, especially when it comes to taxpayer money matters, for fear that a future Democratic president will declare a national emergency to reroute funds to climate change plans or gun control measures.

“There are some people that think any time you take exception to the position the president may have taken, you’re being disloyal. I don’t believe that,” Tillis said in an interview Tuesday. “I’ve had a great discussion with the White House in the past week or so. They understand that I know there’s a crisis at the border.

“It’s never a tough vote for me when I’m standing on principle.”

But the Senate vote to disapprove Trump’s emergency declaration is among the first in what may be several over the next two years that will force GOP senators up in November 2020 to balance their allegiance to Trump’s agenda while exercising independence from him when politically necessary.

This vote also comes on the highly charged issue of immigration and Trump’s signature campaign promise of a border wall, although he repeatedly said during his 2016 presidential campaign that Mexico would pay for it. Trump has recently warned that Republicans who defy him on the national emergency will “put themselves at great jeopardy.”

Homeland Security Secretary Kirstjen Nielsen reportedly met with Republican senators a day after Deputy Director of Government Communications Zach Parkinson told staffers senators should “keep their powder dry” ahead of the vote as the administration labors to limit defections.

With the vote already all but decided, the White House would like to limit how many more Republican Senators defy the president with another vote against him.

“If I voted to disapprove it, it would basically say I am not for what the president is trying to accomplish at the border — which I am for,” said Sen. John Cornyn (R-Tex.), a former member of leadership who is up for reelection next year. He initially urged Trump against declaring a national emergency but has since said he would vote against the disapproval measure because the president has the authority to act.

Trump declared a national emergency on Feb. 15, looking to move $3.6 billion dollars already allocated for military construction projects. The administration also is looking to access $601 million from a forfeiture fund in the Treasury Department and $2.5 billion more from a Pentagon counterdrug account, which it can already do without an emergency declaration.

Despite the embarrassing rebuke, Trump can veto the resolution and neither the House nor Senate will have the two-thirds super majority needed to override a presidential veto.

“Each of our members is going to be casting a vote that they believe is right,” said Sen. Todd C. Young (R-Ind.), the chairman of the National Republican Senatorial Committee.

But inside party lunches, particularly on Tuesday, the administration has made the hard sell to senators by depicting a crisis at the border — underscored by the release of statistics Tuesday that show the number of people apprehended at the southern border spiked an additional 31 percent last month.

Nielsen described the influx of unaccompanied minors and migrant families at the border and tied it to the administration’s case for constructing additional barriers, according to senators who attended the lunch and others briefed on it.

She stressed that the emergency declaration was necessary and while the administration expected legal challenges, that was still not a reason to abandon the declaration, according to an official familiar with her presentation who spoke on the condition of anonymity to discuss private deliberations.

But Trump’s border wall — and his chosen method to tap money for it — remains broadly unpopular in public polling.

An NBC News/Wall Street Journal poll released Sunday found 60 percent of the public opposes Trump’s decision to declare a national emergency to build his wall, while 39 percent back it.

The wall’s popularity fluctuates among various states. In Iowa, a perennial presidential swing state which will also host a likely competitive Senate race, a recent Des Moines Register/Mediacom poll found an increase in support for building a wall “no matter what else is happening with immigration policy” from 30 percent a year ago to 37 percent in February.

“I’m leaning toward supporting the president. I do think we have a humanitarian crisis,” Sen. Joni Ernst (R-Iowa), who is on the ballot next November, said Tuesday. “So many people I hear from say, ‘Build that wall. Support the president.’ ”

Sen. Cory Gardner (R-Colo.), who is up for reelection next year in a state that Hillary Clinton won in 2016, declined on Tuesday to say how he would vote on the disapproval resolution. He stressed his decision would be independent of political considerations: “I get asked if I walk the dog more because of my reelection. I do what’s right for the country, the Constitution and Colorado.”

But one of his potential Democratic challengers made it clear in an interview Tuesday that Gardner’s vote could pose a political liability.

“I think Coloradans are clear that they do not see this as the emergency that matters in this country,” said Mike Johnston, a former state senator who announced his candidacy for the U.S. Senate in January. He called Trump’s emergency declaration “clearly unconstitutional.”

Ultimately, it looks like that will be up to the Supreme Court to decide.