Syria resolution is no sure thing in the Senate. Here’s why.

President Obama's request for Congress to authorize the use of military force in Syria has hit tough sledding -- particularly in the GOP-controlled House.

But increasingly, it's looking like it might also face more immediate problems in the Democratic-controlled Senate.

Senate Majority Leader Harry Reid (D-Nev.). (The Washington Post)

Senate Majority Leader Harry Reid (D-Nev.). (The Washington Post)

Sen. Heidi Heitkamp (D-N.D.) on Monday became the sixth Senate Democrat to announce her opposition to the resolution. And by the end of the day, the number of senators opposed to or leaning against military action in Syria hit 33 -- with 25 senators in favor.

(See our handy-dandy whip count here.)

So what are the prospects from here?

For the sake of argument, let's assume those 58 senators are ensconced in their "yes" or "no" positions. They may change, but we've got a pretty good idea where they stand right now.

We took a close look at the other 43 senators currently listed as "undecided," talked with some smart folks (read: Paul Kane), and came to a few conclusions:

1. Of the 15 GOP senators currently in the undecided column, we would be very surprised to see five of them vote "yes," given their voting records, home states and political situations. Those five are: Sens. Deb Fischer (R-Neb.), Mitch McConnell (R-Ky.), Tim Scott (R-S.C.), Jeff Sessions (R-Ala.) and Richard Shelby (R-Ala.).

Assuming those five vote "no," that would leave 10 undecided Republicans who are on the table. If they joined the current seven GOP supporters of military action, that would mean a maximum of 17 Senate Republicans would support action in Syria.

And if that were the case...

2. Democrats would need at least 34 out of 54 Senate Democrats to get to a majority -- in other words, at least 16 of the 27 undecided Democratic senators. (For the purposes of this exercise, Democratic-caucusing independent Sen. Angus King is a Democrat.)

That may not seem like a tough haul -- given that this is Obama's own party -- but look at some of the folks on this list of 27:

* Noted liberals like Sens. Tammy Baldwin (D-Wis.), Elizabeth Warren (D-Mass.), Mazie Hirono (D-Hawaii), Ed Markey (D-Mass.), Jeff Merkley (D-Ore.) and Ron Wyden (D-Ore.).

* Senators facing reelection in 2014 in tough states, including Sens. Mark Begich (D-Alaska), Mary Landrieu (D-La.) and Mark Udall (D-Colo.). And future top GOP targets like Sens. Michael Bennet (D-Colo.), Joe Donnelly (D-Ind.), Jon Tester (D-Mont.) and Claire McCaskill (D-Mo.).

* Retiring Democratic senators in red states: Sens. Jay Rockefeller (D-W.Va.), Tim Johnson (D-S.D.) and Max Baucus (D-Mont.).

* Potential 2016 presidential hopefuls, including Warren and Sens. Kirsten Gillibrand (D-N.Y.) and Amy Klobuchar (D-Minn.).

If there's anything that the vote count so far has shown us, it's that people in these categories have been among the most likely members to oppose military action. That's not to say all (or most) of them will oppose it -- just that it's no cinch that 16 of the 27 undecided Democrats will eventually come around.

And don't forget, if fewer than 17 Senate Republicans are on board, Democrats will need even more of these members. If just 12 total Republicans support it (a more likely scenario than 17 GOP supporters), Democrats would need to secure 21 of the 27 undecided Democratic votes.

And none of the above brings into account the power of...

3. The filibuster. Passing the Syria use-of-force resolution is about getting to 51 senators, but it's also about making sure that 41 senators don't join forces to prevent it from coming to a final vote.

Given that some of the opponents will be Democrats, it seems less likely that they would band together with Republicans -- who won't have the power to filibuster by themselves -- and oppose bringing the resolution to a vote.

But military force is a very powerful issue, and it's not inconceivable that some of these Democrats who feel strongly about the matter or are concerned about the political price of opposing a filibuster could potentially be brought on board.

All of these scenarios -- we must emphasize -- are highly subjective and speculative. It's still relatively early, and much will come into focus in the days ahead.

But given the thrust of this debate and of public opinion -- which is more than two-to-one against military action in Syria -- we really shouldn't assume this resolution passes in either chamber at this point.

Fixbits: 

It's Election Day in New York and Colorado! Here's what you need to know.

A New York Times/CBS News poll shows widespread opposition to military intervention in Syria.

Former secretary of state Hillary Clinton is on the same page as Obama when it comes to Syria.

Sen. Ted Cruz (R-Tex.) will be busy when he returns to Iowa next month. He'll go to a state party fundraiser, a pheasant hunt and a fundraiser for Rep. Steve King (R-Iowa).

Rep. Mark Sanford (R-S.C.) won an exemption to take his fiancee on an all-expenses trip to Israel.

Howard Dean will co-host a fundraiser for Georgia Democratic Senate candidate Michelle Nunn.

The DCCC added nine names to its program on the top recruits. Seven are women.

Must-reads:

"Obama administration’s message on Syria is muddled" -- Zachary A. Goldfarb, Washington Post

"Obama’s push for Syria action runs into growing opposition" -- Paul Kane and Ed O'Keefe, Washington Post

Also on The Fix

The eight important quotes from Obama's Syria interviews