With President Obama speaking about his new federal health care law in Maryland Thursday, Republicans plan to hit vulnerable Democratic senators for supporting a government spending bill that included funding for Obamacare.

The National Republican Senatorial Committee plans to blast Sens. Mary Landrieu, D-La.; Kay Hagan, D-N.C.; Mark Pryor, D-Ark., Mark Begich, D-Alaska; and Jeanne Shaheen, D-N.H., for opposing a Republican effort to defund Obamacare in a new government funding bill. All are expected to vote later this week to strip the defunding provision from the bill.

"This weekend we will see the Republican Party stand with the American people and vote against Obamacare," a committee aide said. "Endangered Democrats will face a very difficult scenario and make their choice."

There's no provision in the budget bill that specifically funds the health care law, as that spending was approved when the reforms were first approved. Still, Republicans pushed the symbolic attempt to defund Obamacare and now say Democrats who continue to support the unpopular health care reforms are taking a political risk ahead of the 2014 elections.

"Landrieu will now have a small window of opportunity to either dismantle Obamacare once and for all, or double down on this costly overhaul," says an NRSC statement being issued Thursday.

Republicans view their Obamacare-centric strategy as politically deft: Polling shows not only that the health care law remains widely unpopular, but that it will be a driving political issue during the 2014 midterm elections. Republicans hope to use the issue to raise campaign cash and sway voters.