Former Republican vice-presidential candidate Sarah Palin has thrown her support behind frontrunner Donald Trump for the party’s presidential nomination.

Ms Palin is a former governor of Alaska, now a conservative political commentator, who has gained a strong supporter base in the crucial state of Iowa.

The coveted endorsement comes less than two weeks before votes are cast in Iowa, the debut contest in the presidential primary race.

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“I am proud to endorse Donald J. Trump for President of the United States of America,” Ms Palin said in a statement distributed by the Trump campaign.

Mr Trump said in the statement he was “greatly honoured to receive Sarah’s endorsement”.

“She is a friend and a high-quality person whom I have great respect for. I am proud to have her support,” Mr Trump said.

Ms Palin has played the role of political powerbroker since her unsuccessful vice-presidential bid, and it was expected that she would appear alongside Mr Trump at a campaign rally in Ames, Iowa, on Tuesday night.

Ms Palin’s support nod is seen as a snub to conservative Senator Ted Cruz, who is neck and neck with Mr Trump in Iowa and running second to him nationally.

Perhaps in an attempt to manage the pending endorsement, Mr Cruz tweeted his appreciation for Ms Palin.

“Without her support, I wouldn’t be in the Senate,” he wrote.

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

In two weeks, the voters of Iowa will be the first in the nation to vote for both the Republican and Democratic parties’ nominees.

Mr Trump is in a tight contest with Mr Cruz for the support of Iowa Republicans, who lean conservative and whose evangelical Christians comprise a major voting bloc.

Ms Palin was in her first term as governor of Alaska in 2008 when Senator John McCain of Arizona, the Republican nominee in that year’s presidential election, picked her as his running mate.