Conservative Republicans and outside advocacy groups spent the summer pushing Congress to defund President Obama's health care law and hoped to carry that momentum into September, when Congress could vote on it. But they now face an unexpected obstacle: The all-consuming debate over military intervention in Syria.

The push to defund Obamacare as part of budget debates this fall has been a defining issue for some rising Republican stars such as Sen. Ted Cruz, R-Texas, who is widely viewed as a potential 2016 presidential contender. And Republicans are hoping Obamacare will prove a major political liability for Democrats in the 2014 mid-term elections.

Conservative groups have spent vast resources during Congress' August recess on campaign-style events and advertising urging lawmakers to defund the law, even if that effort derails budget negotiations and forces the federal government to shut down.

Heritage Action, the political arm of the Heritage Foundation, underwrote a cross-country “Defund Obamacare Town Hall Tour," and the Republican National Committee launched a website, "Obamacare Costs."

Likewise, the influential Club for Growth remains “100 percent focused on supporting the efforts of Ted Cruz, Mike Lee, Marco Rubio and others to defund and stop Obamacare,” said Club spokesman Barney Keller.

Progressive groups have also focused on Obamacare to counter Republican opposition and raise public awareness of new health care rules that take effect next year. Former President Bill Clinton spoke about the law in Arkansas this week, while Organizing for Action, Obama’s political arm, staged a variety of health care-related events.

Despite expending all of that political energy over the summer, both sides now must overcome a packed congressional schedule. Lawmakers have only nine work days scheduled for September during which they must negotiate a temporary budget bill to prevent the government from shutting down and raise the nation's debt ceiling before the government defaults on its financial obligations.

Added to those time constraints now is the din of the debate over Obama's call for a military strike against Syria in retaliation for it use of chemical weapons against its own citizens.

“The worst scenario would probably be if authorization is approved for Syria or the president decides to do it anyway, and we’re in the midst of a serious military conflict when the [temporary budget bill containing Obamacare funding] comes up,” an aide to a conservative House member said. In that scenario, the aide added, supporters of defunding Obamacare would likely hold off on their legislative push for a month or two.

Still, the outside groups that have staked so much on the health care debate, and especially those conservative groups that have garnered attention for their efforts to defund the law, are hoping the issue will nevertheless break through.

“We certainly expect that members of Congress can do more than one thing at one time,” said Heritage Action spokesman Dan Holler. “Maybe that’s optimistic.”

Holler added, “Our job primarily is to make sure members of Congress don’t come back to Washington and forget everything they’ve heard from their constituents over recess.”