The US Senate has rebuked US President Donald Trump by voting to end his border emergency declaration, as 12 Republicans joined Democrats to deliver a second blow to the president, who quickly pledged a veto.

The 59-41 vote was a bipartisan repudiation of Mr Trump’s decision to circumvent Congress and take money already designated for other programs and redirect it to pay for his US-Mexico border wall, which he promised to build during his 2016 campaign.

In the first two years of his term, the Republican-led Congress mostly accommodated Mr Trump, which spared him from having to use his veto pen.

With Republicans showing increased willingness to defy him, Mr Trump promised a change.

“VETO!” he tweeted shortly after the vote.

I look forward to VETOING the just passed Democrat inspired Resolution which would OPEN BORDERS while increasing Crime, Drugs, and Trafficking in our Country. I thank all of the Strong Republicans who voted to support Border Security and our desperately needed WALL!

— Donald J. Trump (@realDonaldTrump) March 14, 2019

The vote on Friday (Australian time) marked back-to-back defeats for Mr Trump in the Republican-controlled Senate.

On Thursday (Australian time), senators approved a resolution seeking to end US support for a Saudi Arabia-led coalition in the war in Yemen, rejecting Mr Trump’s policy toward the kingdom.

“Today’s votes cap a week of something the American people haven’t seen enough of in the last two years,” Senate Democratic leader Chuck Schumer told reporters.

“My hope is that this past week isn’t an aberration, but a turning point.”

A House of Representatives leadership aide said there would likely be a vote to attempt to override Mr Trump’s promised veto on March 26 after lawmakers return from a one-week recess.

The measure is unlikely to become law as there are enough Republicans in the House and Senate to sustain a Trump veto, which requires a two-thirds majority in both chambers to override.

The issue could ultimately be decided by the courts.

Mr Trump has made clamping down on illegal immigration a cornerstone of his presidency and it promises to be central to his 2020 re-election campaign.

His drive for billions of dollars to build a US-Mexico border wall – one that he initially promised Mexico would pay for – has placed a wedge between him and Congress, including many Republicans who are uncomfortable even talking about a “wall.”

Many in Congress say effective border security requires a range of law enforcement tools.

At stake are billions of dollars in funding for barriers along the US-Mexico border that Mr Trump is demanding but Congress has refused to fully provide.

The stalemate led to a 35-day partial government shutdown that ended in January.

Under the emergency declaration he signed on February 15, Mr Trump would take money from other federal programs to build the barrier, which he says is needed to curb illegal immigration and drug trafficking.

Democrats deny there is an emergency at the border, saying border crossings are at a four-decade low.

-AAP