For vulnerable Senate Democrats, the upcoming vote to authorize limited military strikes on Syria will mark a high-profile opportunity to buck Republican criticism by going against President Barack Obama on a major legislative proposal.

But, so far, few have jumped at that chance.

One of those incumbents, Sen. Mark Pryor, who faces a tough re-election fight in Arkansas in 2014, announced over the weekend that he would vote "no" on the resolution to authorize military intervention.

"I have said, before any military action in Syria is taken, the administration must prove a compelling national security interest, clearly define a mission that has a definitive end-state, and then build a true coalition of allies that would actively participate in any action we take," Pryor said in a statement. "Based on the information presented to me and the evidence I have gathered, I do not believe these criteria have been met, and I cannot support military action against Syria at this time."

Pryor's Republican challenger, Rep. Tom Cotton, has publicly supported military intervention, making it likely the issue will find its way into their race, both sides said.

Another at-risk incumbent, Sen. Kay Hagan, D-N.C., took the opposite approach when, early in the debate, she declared support in principle for limited military action, although she has not yet announced full backing for the resolution before Congress.

"Without putting American troops on the ground, the atrocities in Syria require a strong response that will prevent them from happening again and ensure that Syria's chemical weapons stockpile does not fall into the hands of terrorists and further destabilize the Middle East," Hagan said.

Most other at-risk Democrats have so far avoided taking a definitive stance — or any stance at all.

"No decision yet," Matt Lehner, a spokesman for Sen. Mary Landrieu, D-La., said Monday.

Likewise, Sen. Mark Begich, D-Alaska, remains undecided.

The issue has been a tricky one for some Republican incumbents as well, including Senate Majority Leader Mitch McConnell, R-Ky., who has yet to announce how he will vote.