New Hampshire was ground zero Tuesday for the ongoing political debate over optional Medicaid expansion in the states, as ordered under Obamacare.

The New Hampshire House of Representatives on Tuesday approved the expansion, just as Vice President Joe Biden happened to be traveling the state — and, during a stop in Nashua, he expressed his thanks for the vote.

“That’s going to change the lives of an awful lot of people," Biden said, according to a pool report.

The measure, having received support from the Democratic-led New Hampshire House and Republican New Hampshire Senate, will be signed by Gov. Maggie Hassan, a Democrat.

If it created a triumphant moment for Biden on Tuesday, however, the bipartisan support in New Hampshire for expanding Medicaid put former Massachusetts Sen. Scott Brown, the probable Republican candidate for Senate in New Hampshire, in a tricky spot politically.

Brown, who has staked much of his fledgling candidacy on opposing Obamacare, did not outright oppose the expansion when he answered a question at Frisbie Hospital in Rochester, N.H., on Tuesday, but he did continue to criticize the overarching health care law of which the expansion is one part, saying, "We would not be in this situation if Obamacare had not moved forward."

While noting that he "believe[s] there needs to be a safety net for people," Brown likened the expansion of Medicaid to the president's pledge that if Americans were happy with their health care plans, they would be able to keep them under Obamacare — a promise that in many cases turned out not to be true.

"I have told people — and I would tell not only this legislature, but every legislature throughout the country — be very, very careful about the promises that the president and this administration are making when it comes to funding," Brown said. "Their concerns are, what happens at the end of three years? Is it then going to be an unfunded federal mandate, that the citizens of New Hampshire will have a whole new program that they didn’t really want? They want to be compassionate, but they really didn’t want this plan — and how are they going to pay for it?"

Under current law, the federal government will pay 100 percent of the cost to expand Medicaid in states through 2016. After that, federal funding for the expansion will gradually decrease until 2020, when it will be set at 90 percent unless Congress adjusts it. There has been no indication from the president or Congress that funding for the Medicaid expansion will be withdrawn, and states could conceivably reject the expansion were federal funding to dry up.

After Brown's remarks, Julie McClain, a spokeswoman for the New Hampshire Democratic Party, said he "is basically not taking a position, or trying not to take a position," rather than admit he doesn't support expanding Medicaid. In a statement earlier Tuesday, New Hampshire Democratic Party Chairman Ray Buckley charged that Brown would not support a Medicaid expansion in New Hampshire and "block health care for thousands of people in New Hampshire" because of his strong anti-Obamacare stance.

Brown is challenging Sen. Jeanne Shaheen, the Democratic incumbent, in one of the prominent Senate races of the midterm election cycle.

Medicaid expansion has become a political lightning rod in the states, where state legislatures and governors have faced a choice between accepting federal dollars for the program or rejecting them — and possibly making an implicit statement about Obamacare in the process. In spite of the potential political blowback, some Republican governors have accepted the money.