Betsy DeVos testifies before the Senate Health, Education and Labor Committee confirmation hearing to be next Secretary of Education on Capitol Hill in Washington, 17 January 2017 Reuters/Yuri Gripas

The tie-breaking vote of US Vice President Mike Pence was required for the senate to confirm Betsy DeVos as education secretary. Republicans had only 50 votes backing DeVos with the defections of GOP Senators Susan Collins and Lisa Murkowski despite a last minute party push to rally support.

In casting the deciding vote, Pence made history as the first vice president to break a senate tie over confirming a cabinet nominee.

Democrats had debated throughout Monday night (6 February) and into Tuesday morning in a bid to block the confirmation, after the defection of the Republicans, under the rallying cry "Just one more."

"I appreciate the Senate's diligence & am honored to serve as @usedgov Secretary. Let's improve options & outcomes for all US students," said DeVos in a tweet after the vote.

A billionaire Republican donor with scant experience in public education, DeVos is the most controversial nominee for the position in recent history, with a grass roots campaign organised to oppose her confirmation.

"I have heard from thousands — truly thousands — of Alaskans who shared their concerns about Mrs. DeVos as secretary of education," Murkowski said on the Senate floor last Wednesday. "They've contacted me by phone, by e-mail, in person, and their concerns center, as mine do, on Mrs. DeVos's lack of experience with public education and the lack of knowledge that she portrayed in her confirmation hearing."

She was widely criticised after claiming in her confirmation hearings that schools in Wyoming might need firearms "to protect against potential grizzlies" when quizzed about the 2013 sandy Hook massacre, in which 20 children were killed by a gunman.

She also struggled to answer questions about federal laws protecting disabled students, and would not commit to upholding guidance issued by the Obama administration on combating sexual assault on campus.

Critics have also pointed to her role in bankrolling school vouchers, which it is claimed take money from education public institutions to pay for tuition at private and religious schools.

She described records showing her to be vice president of a foundation that funds anti-LGBTQ organisations and 'gay conversion' therapy were as a "clerical error".

President Donald Trump tweeted his support for DeVos ahead of the vote: "Senate Dems protest to keep the failed status quo. Betsy DeVos is a reformer, and she is going to be a great Education Sec. for our kids!"