"This is it. We have got to come together. Because this is the year when we make Barack ObamaBarack Hussein ObamaOvernight Energy: Dems ask Pruitt to justify first-class travel | Obama EPA chief says reg rollback won't stand | Ex-adviser expects Trump to eventually rejoin Paris accord Overnight Regulation: Trump to take steps to ban bump stocks | Trump eases rules on insurance sold outside of ObamaCare | FCC to officially rescind net neutrality Thursday | Obama EPA chief: Reg rollback won't stand Ex-US ambassador: Mueller is the one who is tough on Russia MORE a one-term president," Bachmann said.

The four-term congresswoman mounted her own bid for the Republican nomination, but ultimately abandoned that effort after she was unable to secure a win in Iowa, her home state.

On the campaign trail, Bachmann was a frequent critic of Romney, chastising the frontrunner on social issues. Romney's refusal to sign a pledge from the Susan B. Anthony List - a prominent conservative anti-abortion group - because frequent fodder for Bachmann on the campaign trail.

But the congresswoman told Huckabee she felt confident that with Romney, evangelicals would have a voice in the White House.

"We will see an open ear from Mitt Romney," Bachmann said. "So far, he has proved to be a person who listens. That's what we need, a nominee who listens."

Bachmann's endorsement could help Romney coalesce some of the Tea Party elements of the party that have so far been reluctant to openly campaign or fundraise on his behalf.

Wednesday night, fellow former rival Rick Perry signaled that he would be endorsing Romney's presidential bid. Newt Gingrich and Rick Santorum have both signaled that they are likely to endorse in the near future, while former contenders like Tim Pawlenty, Herman Cain, and Jon Huntsman already signaled their support for the former Massachusetts governor.