Publicly and privately, an increasing number of Democrats are signaling they won’t go along with the resolution, at least not right now. While just six Senate Democrats have publicly announced their opposition, that number could increase dramatically in coming days, Democratic sources say. …

But a mass defection among Senate Democrats could force the White House to turn to Republicans to push the Syria resolution through the chamber. …

Yet on Monday, six senators — Republicans Lamar Alexander (Tenn.), Johnny Isakson (Ga.), Mike Enzi (Wyo.), Roger Wicker (Miss.) and Roy Blunt (Mo.), as well as Democrat Heidi Heitkamp (N.D.) — all came out against the Syria resolution, while Democrats Barbara Mikulski (Md.) and Martin Heinrich (N.M.) announced they’d back it.

In addition, a number of other Democrats are officially undecided, and the White House fears they may vote against the measure. These include Sens. Jon Tester of Montana, Elizabeth Warren of Massachusetts, Tim Johnson of South Dakota, Mary Landrieu of Louisiana, Richard Blumenthal of Connecticut and the independent Angus King of Maine.