ObamaCare is at the center of a rapidly escalating fight that threatens to shut the government down this fall.

Senate Republicans, including two members of the leadership, are coalescing around a proposal to block any government funding resolution that includes money for the implementation of the 2010 Affordable Care Act.

But such a move is a nonstarter for President Obama and congressional Democrats. Republicans have tried this maneuver in Obama’s first term, only to back off later to the chagrin of Tea Party leaders.

This time, GOP lawmakers are emboldened by problems plaguing the administration’s ObamaCare implementation. But that zeal could put Speaker John Boehner (R-Ohio) and Minority Leader Mitch McConnell (R-Ky.) in a tough spot. Both leaders have downplayed previous talk of shuttering the government.