WASHINGTON: Massachusetts’ Democratic Sen. John Kerry, who unsuccessfully sought the presidency in 2004 and has pined to be America’s top diplomat, has vaulted to the head of President Barack Obama’s short list of secretary of state candidates.

That’s after UN Ambassador Susan Rice suddenly withdrew from consideration Thursday to avoid a contentious confirmation fight with Republicans.

The exit of Rice, and elevation of Kerry, was coupled with the potential for even bolder second-term changes in Obama’s national security team. Chuck Hagel, a former Republican senator from Nebraska, has emerged as the front-runner to serve as defense secretary.

The possible selection of Kerry and Hagel would put two decorated Vietnam War veterans — one Navy, the other Army — at State and the Pentagon.

Announcements could come as early as next week.

Susan Rice, the embattled UN ambassador, abruptly withdrew from consideration to be the next secretary of state after a bitter, weeks-long standoff with Republican senators who declared they would fight to defeat her nomination.

The reluctant announcement makes Massachusetts Sen. John Kerry the likely choice to be the nation’s next top diplomat when Hillary Rodham Clinton departs soon. Rice withdrew 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.

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 defense secretary, with official word expected as soon as next week.

For the newly re-elected president, Rice’s withdrawal was a sharp political setback and a sign of the difficulties Obama faces in a time of divided and divisive government. Already, he had been privately weighing whether picking Rice would cost him political capital he would need on later votes.

When Rice ended the embarrassment by stepping aside, Obama used the occasion to criticize Republicans who were adamantly opposed to her possible nomination.