Sen. John McCain on Thursday threatened to block a second term for Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, after a testy exchange over the Obama administration's response to the Syrian civil war.

McCain, a member of the Senate Armed Services Committee and a former presidential candidate, told reporters he would place a hold on Dempsey's nomination for a second two-year term unless the general divulges his private opinions on the best policy for the White House to take on Syria.

During a confirmation hearing earlier Thursday, Dempsey sidestepped questions from McCain and other Republican senators about what course of action he has recommended that President Barack Obama take in Syria. Dempsey said that the administration is still weighing its options and that "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."

Dempsey's response frustrated McCain, who said the general had pledged to share his personal views with the Armed Services Committee even if they were at odds with the administration's public stance. "I want him to answer the question," McCain said after the hearing. He said he would block a vote on the renomination "until Gen. Dempsey responds to the legitimate questions that he committed to do."