Mike Huckabee was seen as one of top Republican contenders to challenge President Barack Obama. [GETTY]

Republican Mike Huckabee has announced that he will not be running in the 2012 presidential elections to challenge US President Barack Obama.

"All the factors say 'go', but my heart says 'no' and that's the decision that I have made", Huckabee said on his Fox News Channel television show on Saturday.

"My answer is clear and firm: I will not seek the Republican nomination for president this year", he added.

The former Arkansas governor was the Republican winner of the crucial Iowa caucuses in 2008 but was unsuccessful in winning his party's nomination, eventually won by John McCain.

Huckabee, who was also formerly a Baptist minister, has since enjoyed much media success as anchor of a popular television show for the Fox channel.

He was seen as one of the top contenders for the Republican Party's 2012 candidacy against Obama's bid for reelection.

Obama has seen a soar in his approval ratings, hitting its highest point in two years - 60 per cent - after the recent killing of al-Qaeda leader Osama bin Laden in Abbottabad, Pakistan.

Newt Gingrich, former Speaker of the US House of Representatives, is set to join the presidential race, as well as Congressman Ron Paul, who is popular with the ultraconservative tea party movement.

But the Republican party has yet to find a clear favorite to run against the incumbent president.