WASHINGTON – Senate Democrats on Wednesday turned aside a bid by Republicans to repeal the new health care law in the first Senate test of the sweeping overhaul that President Obama signed in March.

The 47-51 party-line vote on a procedural motion came two weeks after House Republicans pushed a repeal resolution through that chamber.

And it ended the first chapter of the GOP legislative attack on the overhaul, setting the stage for new battles over specific provisions of the law, including the controversial mandate that will require most Americans to get health insurance starting in 2014.

Both of Maine’s Republican senators voted for repeal.

Sen. Susan Collins said her vote was based on some of the same reasons that led her to oppose the reform legislation in the first place. Collins said she favors “starting anew” on health care reform.

She said there are plenty of areas of bipartisan agreement on reform, such as tax credits for self-employed individuals and small businesses to help buy insurance coverage, and a ban on denial of coverage based on pre-existing conditions.

“One of the major reasons I opposed the health care law was that it did not do enough to rein in the cost of health care and to provide consumers with more affordable choices,” Collins said in a written statement. “As it turns out, the law will impose billions in new taxes, fees and penalties and lead to fewer choices and higher costs for many middle-income Americans and most small businesses.”

Collins said she hopes lawmakers will continue to look at changes to the law, such as Wednesday’s 81-17 vote to eliminate the provision adding tax filing paperwork requirements for small businesses. She was referring to a provision requiring businesses to report purchases exceeding $600 to the IRS.

Sen. Olympia Snowe, R-Maine, said both the bills she voted for Wednesday, the one to repeal the paperwork requirements and the one to repeal the entire law, would lessen burdens placed on individuals and small businesses by the health care law.

“Only after we repeal this bill can we advance workable reforms that would result in more competitive health insurance markets by expediting the ability of individuals and small businesses to purchase health insurance across state lines . . . and that would inject unfettered competition and new coverage options into stagnant insurance markets like those in Maine,” Snowe said in a written statement.

She said lawmakers should “also develop a plan for affordability by maintaining certain widely agreed upon elements of reform — such as outlawing unconscionable insurance industry practices, banning pre-existing condition limitations, and allowing parents to keep children on plans until age 26.”

Republican leaders, who have pledged to go after the law “piece by piece,” have not indicated what part of the overhaul they will target first.

With funding for the federal government set to expire in four weeks, the next battleground could be legislation to keep the government operating from March to September.

Short of shutting down the government, Republican leaders are working to peel off enough Democrats in the Senate to pass legislation taking out pillars of the health care law, such as the mandate to purchase coverage and the funding needed to expand coverage to tens of millions of Americans.

Republicans are also considering proposals to allow states to opt out of parts of the law, as many GOP governors have said they want to do.

On Wednesday, the GOP repeal proposal did not win over a single Democrat, as 47 Republicans voted for it and 50 Democrats and one independent voted against it. Democrat Mark Warner of Virginia and Independent Joe Lieberman of Connecticut missed the vote.

Even Democrats from conservative states who face re-election in 2012 staunchly rejected a repeal, though many have said they are interested in modifying the law.

“Who wants to go backwards and tell 220,000 Nebraskans they can’t have health insurance?” Nebraska Sen. Ben Nelson told reporters in his home state Wednesday. “Who wants to deny children health insurance because they have pre-existing medical conditions?”

Republican lawmakers said they would come up with an alternative to the law.

“We’d repeal this bill right now, and then we’d begin the work of achieving our common goal of delivering health care at a higher quality for lower costs,” Senate Minority Leader Mitch McConnell, R-Ky., told his colleagues on the Senate floor. Republicans haven’t yet offered an alternative, however, prompting warnings from consumer groups and patient advocates such as the American Cancer Society that Americans stand to lose new protections if the law is repealed.

Washington Bureau Chief Jonathan Riskind contributed to this report.