CNN

John Kerry, the chairman of the Senate Foreign Relations Committee, praised Chris Hill Wednesday.

WASHINGTON (CNN) – Career diplomat Chris Hill, President Obama's choice to be the next U.S. Ambassador to Iraq, faced opposition Wednesday from powerful Republican senators who could delay or destroy his chances Hill was in otherwise friendly territory for his confirmation hearings before the Senate Foreign Relations Committee.

Committee chairman, Sen. John Kerry, D-Massachusetts, spoke glowingly of Hill and his "long and distinguished "32-year diplomatic career. And Kerry made clear that he thought Hill deserved quick Senate approval.

"I understand that some of my colleagues may be considering holding up a vote on Ambassador Hill's nomination until after the upcoming recess," Kerry said. "Of course, senators have every right to vote against Ambassador Hill.

But I believe that using senate procedures to delay his arrival to Baghdad at a critical time in this war would do a serious disservice to our efforts there."

The ranking Republican on the committee, Sen. Richard Lugar, R-Indiana, also called for speedy approval and said approving Hill was critical to support the U.S. military in Iraq.

"And we are at war," Lugar said. "This is not a parliamentary struggle among senators who have diverse points of view," Lugar said.

Lugar's support is seen as crucial to Hill's chances to move to Baghdad. But Lugar did ask a question on behalf of one of Hill's strongest critics, Sen. Sam Brownback, R-Kansas, who has accused Hill of failing to promote human rights in his dealings with North Korea.

Hill was U.S. point-man in the difficult negotiations with North Korea about dismantling its nuclear program. Hill said he had pledged to introduce separate human rights discussions but that North Korea's failure to divulge full details of its nuclear weapons program had made that impossible.

Other senators have questioned whether Hill should go to Baghdad, where he doesn't speak the language and has no experience in that region of the world. One powerful opponent is Sen. John McCain, R-Arizona. The former Republican presidential candidate met with Hill last week and is seeking more information from Hill.

"We are submitting questions in writing to him," McCain aide Brooke Buchanan told CNN Tuesday. "We will wait for his response and go from there," Buchanan said.

Kerry said Hill had shown in all his diplomatic posts that he was ready for the new challenge. "Often, the reward for diplomats who succeed in difficult postings with long odds is tougher assignments with longer odds," Kerry said in his opening statement. "Ambassador Hill has made a career, now entering its fourth decade, of tackling seemingly intractable diplomatic challenges.

And make no mistake: Iraq today still presents extraordinary challenges." Kerry said.

Hill has promised to leave the day after Senate approval of his posting to Iraq. And he said his work would honor Americans who had lost their lives in Iraq. "I will always keep in mind and in my heart the fact that over 4,000 of our men and women gave their last, full measure to this effort.

For their memory and for our nation, we must succeed," he said. Asked about how he viewed the challenge of continuing the successes of the past U.S. Ambassador, Ryan Crocker, Hill spoke more bluntly. "I just don't want to screw it up."