Republicans seized on Vice President Joe Biden's Thursday comment that he expects the military prison at Guantanamo Bay, Cuba, to close by the end of President Obama's tenure, which he promised to do his first day in office.

The National Republican Congressional Committee wasted no time in blasting vulnerable Democrats for that pledge, such as Rep. Rick Nolan, D-Minn.

"Nolan has been a steadfast supporter of closing Gitmo, voting as recently as June to give President Obama the authority to close the facility and bring the dangerous terrorists held there to U.S. soil," the NRCC said in a statement.

"It looks like the Obama administration is granting John Delaney his wish of closing Gitmo and bringing dangerous terrorists to the United States," read another one targeting Maryland Democrat John Delaney. "Now that Vice President Joe Biden admitted the prison will close, Marylanders will be facing the consequences for John Delaney's blind partisanship."

In the face of congressional opposition, the Obama administration has picked up the pace of transferring detainees to other countries, lowering the prison's population to just 61 after sending 15 detainees to the United Arab Emirates this month. Obama has left open the possibility of sidestepping Congress by issuing an executive order to close the facility.

White House spokesman Josh Earnest said Thursday that all options allowing Obama to achieve his goal are on the table.

"We're going to do our best to try and get this closed," he said Thursday. "I can't lay out for you the path exactly that that's going to take right now," but it's a priority.

"Congress has erected enormous barriers, and we have to figure out a way to deal with them," he admitted, referring to the laws preventing Obama from moving any remaining detainees to U.S. prisons.