WASHINGTON - With the embattled US Ambassador to the United Nations Susan Rice having withdrawn her name from secretary of state consideration, attention is turning toward Senator John Kerry, a senior Democrat who is the other top candidate to replace outgoing Secretary of State Hillary Clinton, according to political sources.

Rice pulled out when it became clear her political troubles were not going away and support inside the White House for her potential nomination had been waning in recent days, administration officials said.

Republicans opposed to a Rice nomination have bandied about Kerry’s name for weeks, and Thursday, Senate Minority Leader Mitch McConnell told CNN that Kerry would be a “popular choice with the Senate.”

It’s ironic that several prominent Republicans are rallying behind Kerry, just eight years after their party demonised him during his failed 2004 presidential campaign against President George W Bush.

Kerry remembered that experience in a statement he released about Rice.

“As someone who has weathered my share of political attacks and understands on a personal level just how difficult politics can be, I’ve felt for her throughout these last difficult weeks, but I also know that she will continue to serve with great passion and distinction,” Kerry said.

The senior senator from Massachusetts is noted for the experience, gravitas and relationship-building skills that could help him succeed as the United States’ top diplomat. In his current role as chairman of the Senate Foreign Relations Committee, Kerry has travelled the globe on behalf of the Obama administration to mend frayed relationships. Most notably, he has travelled to Pakistan after a series of incidents, including the raid that killed Osama bin Laden.

In another major part of the upcoming Cabinet shake-up for President Barack Obama’s second term, former Republican Sen Chuck Hagel of Nebraska now is seen as the front-runner to be Defence secretary.

But Rice’s withdrawal was a sharp political setback and a sign of the difficulties Obama faces in a time of divided and divisive government.

Obama used the occasion to criticise Republicans who were adamantly opposed to her possible nomination. “While I deeply regret the unfair and misleading attacks on Susan Rice in recent weeks, her decision demonstrates the strength of her character,” he said. “I am saddened we have reached this point,” Rice said.

Obama made clear she would remain in his inner circle, saying he was grateful she would stay as “our ambassador at the United Nations and a key member of my Cabinet and national security team.”

Rice had become the face of the bungled administration account of what happened in Benghazi, Libya, on Sept 11, 2012 when four Americans, including the US ambassador to Libya, were killed in what is now known to have been a terrorist attack. Obama had defiantly declared he would choose her for secretary of state regardless of the political criticism.

Rice may end up close to Obama’s side in another way, as his national security adviser should Tom Donilon move on to another position. The security adviser position would not require Senate confirmation.