By Tracy Connor, NBC News

Embattled U.N. envoy Susan Rice is dropping out of the running to be the next secretary of state after months of criticism over her Benghazi comments.

“Today, I made the decision that it was the best thing for our country, for the American people that I not continue to be considered by the president for nomination of secretary of state,” Rice told NBC’s Brian Williams.

“I didn’t want to see a confirmation process that was very prolonged, very politicized, very distracting and very disruptive because there are so many things we need to get done as a country and the first several months of a second term president’s agenda is really the opportunity to get the crucial things done.”

Rice noted that President Obama’s second-term agenda included “comprehensive immigration reform, balanced deficit reduction, job creation.”

She added, “And to the extent that my nomination could have delayed or distracted or deflected or maybe even some of these priorities impossible to achieve, I didn’t want that and I much prefer to keep doing what I’m doing which is a job I love at the United Nations.”

The full interview with Rice will air on tonight’s “Rock Center With Brian Williams” at 10p/9c. Excerpts will also be broadcast on Nightly News at 6:30 pm ET.

Obama said in a statement that he accepted her decision and regretted “the unfair and misleading attacks” on Rice, who was considered a front-runner to replace Hillary Clinton as the nation’s top foreign policy official.

Criticism over remarks

Rice has been under intense fire from Republicans for initially characterizing the Sept. 11 assault on the U.S. consulate in Benghazi, Libya, as a spur-of-the-moment response to a crude anti-Muslim film.

“What happened in Benghazi was in fact initially a spontaneous reaction to what had just transpired hours before in Cairo, almost a copycat of the demonstrations against our facility in Cairo, which were prompted, of course, by the video,” Rice said on NBC’s “Meet the Press” five days after the attack.

“Opportunistic extremist elements came to the consulate as this was unfolding. They came with heavy weapons, which unfortunately are readily available in post-revolutionary Libya, and it escalated into a much more violent episode.”

As more details emerged suggesting it was a premeditated terrorist action, GOP critics accused Rice of misleading the public at the height of the presidential campaign.

She countered that she went with the best information available about the attack, in which Ambassador Chris Stevens and three other Americans were killed.

“I relied solely and squarely on the information provided to me by the intelligence community. I made clear that the information was preliminary and that our investigations would give us the definitive answers,” she said on Nov. 21 at the United Nations.

By then, Obama had already expressed strong support for Rice, warning Sens. John McCain (R-Ariz.) and Lindsey Graham (R-S.C.) to stop slamming her and vowing to block her confirmation.

“They should go after me,” he said at his first press conference after his re-election.

Despite a series of closed-door meeting with Capitol Hill lawmakers to drum up support, Rice continued to face questions from senators key to her confirmation.

After a Nov. 28 sitdown with Rice, Sen. Susan Collins (R-Maine) said she couldn’t yet endorse the veteran diplomat and raised a new point of concern: her role in protecting American embassies in Kenya and Nairobi that were bombed by terrorists in 1998.

Sen. Bob Corker (R-Tenn.) suggested Rice was seen as too much of an Obama loyalist and the GOP preferred “someone of independence.”

Attack on critics

In her resignation letter to Obama, Rice took aim at her GOP critics.

“The position of secretary of state should never be politicized,” she wrote.

“As someone who grew up in an era of comparative bipartisanship and as a sitting U.S. national security official who has served in two U.S. Administrations, I’m saddened that we have reached this point, even before you have decided whom to nominate. We cannot afford such an irresponsible distraction from the most pressing issues facing the American people.”

Obama praised Rice as “an extraordinarily capable, patriotic, and passionate public servant.”

“While I deeply regret the unfair and misleading attacks on Susan Rice in recent weeks, her decision demonstrates the strength of her character, and an admirable commitment to rise above the politics of the moment to put our national interests first.”

McCain and Graham, among Rice’s loudest critics, said they would continue to press the administration on Benghazi.

“I respect Ambassador Rice’s decision,” Graham said in a statement. “President Obama has many talented people to choose from to serve as our next secretary of state.”

The withdrawal leaves Sen. John Kerry (D-Mass.) as a possible candidate for the job, and Republicans have said he would have a smoother run.

"I think John Kerry would be an excellent appointment and would be easily confirmed by his colleagues," Collins said last month.

Rice, 48, has been the United States’ permanent representative to the United Nations since 2009, after serving as a senior advisor to the Obama campaign, working at the Brookings Institution and holding other diplomatic and national security positions dating back to 1993.