President Obama has mustered limited international support for a military strike on Syria, stirred uncertainty about what he'll do if Congress fails endorse a strike (it may depend on the meaning of "intention") and faces growing Capitol Hill resistance.

All of it serves to further complicate an already-perplexing calculation for a small but vulnerable group of Americans: the half-dozen U.S. senators, all but one of them Democrats, struggling to make a case for their own re-election.

They are balancing the issue of loyalty to the president against the vociferous and largely anti-Syria-strike sentiment back home.

Heading into the week when they will likely be asked to vote on the issue, here's a look at where the most vulnerable-in-2014 senators stand:

Senate Minority Leader Mitch McConnell, R-Ky.

McConnell is the only congressional leader who has not come out in support of Obama's Syrian plan, and he offered no comment after the Senate Foreign Relations Committee on Wednesday voted to authorize the strike.

Before that vote, he said that "Congress and our constituents would all benefit from knowing more about what it is he thinks needs to be done — and can be accomplished — in Syria and the region."

McConnell's fence-sitting has been widely attributed to the primary challenge he faces from Kentucky businessman Matt Bevin, who strongly opposes Syrian intervention with or without congressional approval, and is using the issue to up his statewide name recognition.

A poll in late July found that more than 64 percent of those surveyed had no opinion of Bevin, and McConnell at the time with a nearly 40 percentage point lead among Kentuckians, asked how they would vote in a GOP primary.

Rick Robinson, a Republican strategist and lawyer in Kentucky, says that given McConnell's big lead over Bevin in the polls, primary politics has little to do with the incumbent senator's reticence.

"Having seen the numbers that I've seen in this race, with Sen. McConnell so far ahead of his opponent, I gotta believe that he's looking more at the policy than the politics," Robinson said Friday. "If the numbers are correct, he doesn't need to worry about the primary."

Nonetheless, McConnell continues to pour money into television and radio ads that call into question Bevin's educational and business credentials.

But more worrisome for McConnell now may be a projected general election contest against Democrat Alison Lundergan Grimes, the Kentucky secretary of state who is seeking her party's nomination for the Senate seat.

And Grimes, like McConnell, has not staked out a position on Syria, saying in a statement that she is "continuing to monitor the situation closely."

Sen. Mark Pryor, D-Ark.

Considered by political oddsmakers to be the most vulnerable senator next year, Pryor has not said how he'll vote on a Syria resolution. But he's increasingly given signs of skepticism during back-home encounters with constituents.

Pryor is being challenged by Arkansas Rep. Tom Cotton, a Republican Army veteran who has come out strongly in favor of military intervention.

Here's Pryor: "I don't want to get into another situation like we've seen before where we get into one of these things and it's hard to measure if we're being successful or not. I think the president needs to be very clear on that on the front end and I'm not satisfied in that area yet."

Pryor, who national Republicans have targeted and is already facing an onslaught of GOP attacks for his vote supporting Obamacare, says his support would hinge on the president assembling a robust coalition of allies, and defining the compelling American interest at stake as well as the mission's end.

The National Republican Senatorial Committee has been working to tie Pryor with Obama's agenda; Cotton's support of the president in this instance, and Pryor's potential disagreement, may provide a small complication.

Sen. Mark Begich, D-Alaska

Begich is in the undecided column, and here's what he has said:

"There is simply no justification to use chemical weapons against fellow humans. And that is why I remain hopeful that we can see a unified, international response to [Syrian President Bashar Assad] and his regime. I am pleased to see President Obama seeking congressional approval before employing military force and hope that Congress will engage in a thoughtful discussion as we work towards building some level of consensus in our nation on this issue. As I have said, I do not want any American boots-on-the ground in Syria and we must clearly understand any and all risks that action could cause to the United States and its citizens."

John Roderick, former Anchorage mayor and former chair of the state Democratic Party, says he doesn't believe that the Syrian issue will be a deciding one in next year's Senate race in Alaska.

"But I think Mark should continue to vote no on this — this is a civil war over there, there will be other civil wars, and I don't think our intervention will change the dynamics of that country," Roderick said. "And if Mark votes against the president, it could do him some good."

Sen. Mary Landrieu, D-La.

Another Republican target, Landrieu has not revealed how she'll vote.

Here's what she's said: "Using military force in Syria is a serious matter, and the president is correct to seek Congressional approval. I will carefully examine the facts in the coming days as Congress debates what the appropriate action is."

Sen. Kay Hagan, D-N.C.

Hagan is the only vulnerable senator who has come out strongly in favor of a military strike in Syria, characterizing it as a necessary deterrent.

Here's what she said the day before the Senate Foreign Relations Committee voted to authorize military action:

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