President Donald Trump’s controversial nominee for education secretary, Betsy DeVos, has been confirmed by the Senate by slenderest possible margin.

Vice-President Mike Pence cast the tie-breaking vote to secure her cabinet role, splitting the chamber 50-50.

It was the first time ever that a vice-president has interceded in such a way for a cabinet secretary.

Betsy DeVos, a billionaire who has no experience with public schools, faced a rocky confirmation hearing last month.

Immediately after voting ended, she tweeted: “I appreciate the Senate’s diligence & am honored to serve as @usedgov Secretary.

“Let’s improve options & outcomes for all US students.”

Image source EPA

On February 7, Senate Democrats staged a 24-hour debate to hold up her confirmation.

They hoped their all-night speaking marathon would pressure more Republican senators to oppose the nomination, but their efforts were in vain.

Mike Pence was also the first vice-president to cast a deciding vote in the Senate since 2008, when Dick Cheney voted on a tax adjustment plan.

No Democrats voted in favor of Betsy DeVos. Two Republican senators stood by their plan to oppose her confirmation, leaving the Senate in a deadlock.

Critics say Betsy DeVos is unqualified to run the Department of Education.

The 59-year-old faced intense scrutiny before a Senate committee in January, when she made headlines for noting that a Wyoming school might need a gun to defend against grizzly bears.

Labor unions, rights groups and teaching organizations have also spoken out against her nomination.

Groups including the American Federation of Teachers and the Leadership Conference on Civil and Human Rights held protests against Betsy DeVos outside of Congress on February 6.

She is a wealthy Republican Party donor and a former Michigan Republican Party chairwoman who has long campaigned for education reform in the state.

Betsy DeVos is a champion of charter schools, which are publicly funded but operate outside state school systems.

Her husband Dick DeVos was a chief executive of the beauty and nutrition giant Amway and her brother is Erik Prince, the founder of the controversial private security company Blackwater.

Betsy DeVos is among several of Donald Trump’s cabinet picks whom Democrats have been trying to block from being approved.

Democrats said in January they would target eight of Donald Trump’s nominees based on their lack of qualifications and policy positions.

According to the Washington Post, before Betsy DeVos’ approval, just six of Donald Trump’s cabinet picks had been confirmed, compared with former President Barack Obama’s 12 cabinet secretaries at this point in 2009 and 16 of George W. Bush’s in 2001.

The slowed process is also partly due to the fact that some of Donald Trump’s picks have not completed a lengthy vetting process typically required of Cabinet candidates, which helps identify potential conflicts of interest.

Hundreds of staff positions also remain vacant as the fate of 15 of Trump administration’s nominees hangs in the balance.