Sarah Palin has announced her endorsement for Donald Trump’s presidential bid.

The populist ex-governor of Alaska was the Republican vice-presidential candidate in 2008.

“Are you ready to stump for Trump?” Sarah Palin asked cheering supporters at a campaign rally in Iowa.

Sarah Palin was John McCain’s running mate in 2008 before they lost to Barack Obama.

Despite retiring from politics in favor of a media career, Sarah Palin remains an influential conservative voice.

Officially announcing her endorsement, Sarah Palin said Donald Trump was someone ready to let US troops “kick ISIS’ ass”.

“We are ready for a change,” she told the rally in Ames, Iowa.

“He [DonaldTrump] is beholden to no one but ‘we, the people’. He is perfectly positioned to let you make America great again.”

Donald Trump, who leads the Republican race, said in a statement that he was “proud” to receive Sarah Palin’s backing.

She was a “trusted conservative” with a “proven record of being fiscally modest, staunchly pro-life and [she] believes in small government that allows businesses to grow and freedom to prosper”, the statement added.

Sarah Palin was just two years into her Alaskan governorship when she was picked by John McCain to be his running mate.

The self-described “hockey mom” soon garnered huge crowds and massive media attention.

After the election in 2009, Sarah Palin resigned as Alaska governor and has since forged a lucrative career as a writer and political commentator.

Ahead of the announcement, Sarah Palin tweeted a link to an article by her daughter Bristol attacking Donald Trump’s main rival for the key Iowa caucus, Ted Cruz.

Iowa is the first chance for voters to have their say in the nomination race.

Ted Cruz has himself praised Sarah Palin saying “without her support, I wouldn’t be in the Senate” – a reference to her backing that helped him to his surprise victory in a 2012 Senate run-off election.

“Regardless of what she does in 2016, I will always be a big fan,” Ted Cruz tweeted.

Democratic frontrunner Hillary Clinton’s campaign team tweeted caustically after the announcement to Sarah Palin “congrats to the YouTube commenter who wrote your remarks”.