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(CNN) —  

House Speaker Nancy Pelosi said Monday if President Donald Trump vetoes the resolution blocking his national emergency declaration, Democrats will respond in Congress and in court.

“We’ll fight him in the Congress, we’ll fight him in the courts and we’ll fight him in the court of public opinion,” Pelosi told reporters at an event in Texas. “What he’s doing is wrong and the Republicans know it.”

The Senate likely has enough votes to pass a measure blocking Trump’s efforts to build a wall on the US southern border through emergency powers. With Republicans controlling 53 seats in the chamber, Senate Democrats need four GOP votes for the measure to pass, and Republican Sens. Rand Paul of Kentucky, Susan Collins of Maine, Lisa Murkowski of Alaska and Thom Tillis of North Carolina have indicated they will vote in favor of the resolution.

Trump has vowed to veto the measure, which was introduced in the House and passed the chamber last week, with 13 Republicans voting with Democrats.

Pelosi’s comments show Democrats have no plans to back down from the fight against allocating billions of dollars for the border wall, which Trump has pursued in fervor as his top domestic priority.

“Hopefully the President won’t veto it – or maybe he’ll just withdraw it, as some of his Republican, the Republican senators are asking him to do because they know that it undermines the Constitution of the United States,” Pelosi said.

Pelosi said Trump is “asking us to ignore the oath of office that we take to protect and defend the Constitution by this declaration.” She said she anticipates the resolution will pass the Senate.

If the President vetoes the measure, Congress would need two-thirds of its members in both chambers to overrule the veto, which is unlikely.

“I think it’s very hard to have a veto,” Pelosi said.

The President signed a spending bill in January that ended the longest government shutdown in US history in January, which did not include the $5.7 billion he had been demanding for his border wall. It did include $1.375 billion for a wall. The President then quickly declared a national emergency, bypassing Congress, to unlock billions in federal funds to build his wall.

Pelosi said Trump’s declaration is “undermining our system of checks and balances,” which she described as the “wisdom of our Constitution.”

CNN’s Ashley Killough, Veronica Stracqualursi and David Siegel contributed to this report.