WASHINGTON - Republicans will make another move today to damage the national health-care law they derisively call Obamacare. This time, they're being aided by the champion of the measure, President Obama.

With Obama's recent move to postpone one part of the law as an opening, the Republican-ruled House of Representatives is expected to vote today to delay more key parts of the contentious measure before it can take full effect.

The move is the latest in a sweeping legislative and political campaign to weaken the 2010 law and raise even more opposition in the eyes of an already skeptical nation, especially as it heads into 2014 elections that will decide control of Congress and set the stage for the 2016 campaign for the White House.

The national party is targeting eight vulnerable Democrats from Alaska to North Carolina up for re-election next year for supporting the law. One major conservative group, Americans for Prosperity, began airing TV ads in key states on the potential dire consequences of the law while another, FreedomWorks, started a national campaign to burn your "Obamacare Draft Card" or peacefully opt out of the law. On Capitol Hill, there are multiple efforts to investigate, repeal, delay.

Republicans probably won't succeed in significantly changing the law - a Democratic-controlled Senate prevents that - but they hope to put a dent in Obama's signature domestic achievement and reap any benefits at the ballot box next year.

Judy Feder, a professor of public policy at Georgetown University who's a nationally recognized leader in health policy, said Republicans were taking advantage of a somewhat minor one-year delay that was "well-received by everyone except Republican lawmakers."

"It's politics," she said. "They want to stir confusion and negative feelings. They want to keep it from working."

It's not a one-sided clash: The administration and its Democratic allies have launched their own national campaign to sell the law.

But the measure remains unpopular. Fifty-two percent of Americans disapprove of the health-care law, according to a Gallup poll this month, up from 45 percent in November.

The House has voted 37 times to repeal the law. Some GOP governors have rejected efforts to expand Medicaid, the government-run health program targeted for expansion in the measure, and they have opposed setting up the required new marketplaces where individuals can buy insurance.

The Republican strategy took on renewed urgency when the Obama administration quietly announced that it would delay the requirement that larger employers offer workers insurance - the so-called employer mandate - on the Treasury Department's website just before the long Independence Day weekend.

"It's a train wreck," said House Speaker John Boehner, R-Ohio. "And even the administration knows that this law is unworkable."

Republicans accuse Obama of delaying the employer mandate to shield vulnerable Democrats from any problems the law might cause before the 2014 elections.

But White House press secretary Jay Carney said it wasn't unusual to alter the schedule of a complex new law after receiving feedback from those involved - in this case employers - and he charged that Republicans were merely trying to further a political agenda.

The House will hold a pair of back-to-back votes today on whether to delay insurance mandates for both employers and individuals. Republicans want to put Democrats on the spot, thinking they'll have a difficult time voting to give a reprieve to businesses and not individuals.