House Minority Leader Nancy Pelosi (D-Calif.) said this week she’s unsure if a majority of her caucus will back President Obama’s proposal to strike Syria.

{mosads}”I don’t know,” Pelosi said in a Tuesday interview with Time magazine published Thursday. “I think it would be important to get a majority in the Congress. But I don’t know if it’s important how you would break it down. These issues are not really partisan.”

Pelosi — one of the most vocal supporters of Obama’s plan to launch missile strikes against Syria in response to President Bashar Assad’s alleged use of chemical weapons on civilians — says Democratic leaders will not formally whip a use-of-force resolution. But she’s been active in making a case for U.S. intervention as both a humanitarian response and a deterrent for similar attacks in the future.

“Hopefully, if this does happen, it will be a message to everyone — the North Koreans, the Iranians, the Syrians, anyone who would use a WMD or threaten to use one — that that’s probably not a good idea,” she told Time.

However, a growing number of liberal Democrats are voicing strong reservations about strikes on Syria, warning that military involvement would be ineffective, cause greater civilian casualties and entrench the United States in yet another Middle Eastern conflict.

Rep. Barbara Lee (D-Calif.), for instance, is a “strong no,” her office said Thursday. In lieu of missile strikes, Lee is crafting legislation promoting a nonmilitary response, focusing on sanctions and an effort to involve the International Criminal Court in The Hague.

On Tuesday and Wednesday, Pelosi sent letters to the members of her caucus asking what changes to the authorization resolution would win their backing.

“Please offer further suggestions or ideas you may have as to what you can support, so I can convey your concerns to the White House,” she wrote Wednesday.

Pelosi is getting little help from GOP leaders. Although Speaker John Boehner (R-Ohio) has both endorsed Obama’s plan and called on Republicans to support it, he’s also made clear that he won’t go out of his way to secure votes for it. That, Boehner’s office has said, is Obama’s burden.

“The Speaker offered his support for the president’s call to action, and encourages all members of Congress to do the same,” spokesman Michael Steel said this week. “Now, it is the president’s responsibility to make his case to the American people and their elected representatives.”

The dynamics have left much of the heavy lifting for Pelosi, as House Republicans are lining up in opposition and a good number of Democrats will almost certainly be needed to get an authorization resolution through the lower chamber.

It’s hardly the first time Pelosi has faced the task of uniting a reluctant caucus behind a tough vote, having shepherded both climate change legislation in 2009 and healthcare reform in 2010 through the House by the slimmest of margins.

Despite her determined efforts to rally support for a Syria resolution, the California Democrat is rejecting the notion that she’s leading the drumbeat to intervention.

“I’m not exactly leading the charge,” she told Time. “But I’m supporting the president.”