WASHINGTON — Republican leaders are betting that the only way for Congress to repeal the Affordable Care Act is to set a bill in motion and gamble that fellow GOP lawmakers won’t dare to block it.

Party leaders are poised to act on the strategy as early as this week, after it has become obvious they can’t craft a proposal that will carry an easy majority in either chamber. Lawmakers return to Washington on Monday after a week of raucous town halls in their districts that amplified pressure on Republicans to forge ahead with their health-care plans.