Mr Paul said at the end of Sunday, in an opinion published on the Fox News website, and again on Monday.
"It's not like I was sitting one day and said," Where do I want to separate myself from President Trump? " "There are political risks to separate the president of his own party," he said, adding: "It is not even immigration, it is not a Republican or a democratic president.
"It's a congress, as opposed to the president, and where power has to be shared," he added.
In his opinion outlining his vote, Paul said that Neil M. Gorsuch and Brett M. Kavanaugh – both conservative judges appointed by Trump to the Supreme Court – turn to the majority to address the enemy. public administration and national emergency declaration.
"The President's order on several walls undoubtedly contradicts the will of the Congress, and certainly the Supreme Court," Paul wrote. "In fact, I think that the President's own choices to the Supreme Court may stop him."
Mr. Trump's statement of urgency – the President was first authorized by the Congress under the National Emergency Act – to refuse funds is a particularly difficult issue.
Like his conservative colleagues, he warned the President not to set a precedent for future democratic presidents to seize the rigorous arms control policies or the tool for controlling climate change. Mr McConnell, on the floor of the Senate, who announced Mr Trump's intention to declare a national emergency and to support the President's decision.
On Monday morning, the White House sent Zach Parkinson, Deputy Director of Government Communications, to meet Republican communication assistants at the meeting, according to two people who asked for anonymity to discuss the private meeting. Mr. Parkinson asked the assistants to "hold dry" the vote and urged the senators to reach the White House House with concern.