By David Alexander and Patricia Zengerle
WASHINGTON (Reuters) - Army General Martin Dempsey's nomination to a second term as the top U.S. military officer hit an unexpected bump on Thursday when a senior Republican lawmaker denounced his stance on Syria during a Senate hearing and vowed to block a vote on the appointment.
Senator John McCain repeatedly questioned Dempsey over his position on the Syrian civil war during a hearing of the Senate Armed Services Committee and criticized him for declining to give the panel his full opinion on whether the United States should intervene in the conflict.
Dempsey said he had presented President Barack Obama with a variety of military options for Syria along with an assessment of the risks. He told McCain the issue of military strikes was under deliberation within the administration.
"It would be inappropriate for me to try to influence the decision with me rendering an opinion in public about what kind of force we should use," he said.
McCain said later he would try to block Dempsey's nomination to a second two-year term as chairman of the Joint Chiefs of Staff, the president's top military adviser, until he responded to questions about whether Washington should provide greater support to opponents of President Bashar al-Assad.
"I'm putting a hold on General Dempsey until General Dempsey responds to legitimate questions," McCain told reporters.
Democrats, who control the Senate 54-46, could break McCain's hold, but they would have to muster 60 votes, which means they would need the help of at least six Republicans.
At this point, Democrats may be inclined to try to meet McCain's concerns since the Arizona Republican helped negotiate a deal earlier this week that helped clear several of Obama's other nominees for confirmation.
McCain repeatedly questioned Dempsey's judgment on Syria during the hearing on his renomination. He frequently interrupted the general with gibes and criticisms, accusing him of stalling, wavering and not responding to questions.
McCain, a former Republican presidential nominee who is one of the Senate's most influential voices on foreign relations and military issues, has been an outspoken advocate for military aid to the rebels fighting Assad.
In May he met with some of the rebels during a surprise visit to the war-torn country.
"Do you believe the continued costs and risks of our inaction in Syria are now worse for our national security interests than the costs and risks associated with limited military action?" the senator asked Dempsey.
When Dempsey responded that the United States was at greater risk because of "the emergence of violent extremist organizations," McCain bluntly replied, "You're not answering the question, general."
"With all due respect, senator, you're asking me to agree that we've been inactive, and we have not been inactive," Dempsey said.
"We haven't used direct military strikes, but we haven't been inactive," he added.
The Obama administration agreed to begin sending some U.S. weapons to Syrian rebels after determining that Assad's forces had used small amounts of chemical weapons against their opponents.
The aid has faced some opposition in Congress and has been slow to reach Syrian rebels.
McCain questioned Dempsey's shifting stance on whether the United States should arm elements of the Syrian opposition, questioning how he accounted for "those pirouettes."
Dempsey said his recommendations had been based on what was known about the Syrian opposition at any given period, noting that extremist elements appeared to be prevailing among the rebel groups at one point early in the year.
When pressed whether the United States should intervene to stop the killings, which have topped 100,000 in the two-year-old war, Dempsey responded by alluding to Iraq.
He asked McCain whether recent experience did not suggest that "situations can be made worse by the introduction of military force" if an intervention is carried out without an effective understanding of how to achieve peace.
(Editing by Mohammad Zargham)