Washington: After seven years of sabre-rattling, Republicans seem set to start muscling legislation through Congress reshaping the country’s health care system.

Don’t confuse that with GOP unity or assume that success is guaranteed. Unresolved disputes over taxes and Medicaid rage and conservatives complaining that Republican proposals don’t go far enough could undermine the effort, or at least make GOP leaders’ lives difficult.

Two House committees — Energy and Commerce, and Ways and Means — plan to begin voting Wednesday on their portions of the legislation, barring late problems. Leaders want to push the package through the House this month and hope the Senate can consider it by Congress’ early April recess.

It’s an ambitious calendar for what could be the year’s most momentous congressional battle.

Repealing President Barack Obama’s 2010 health care overhaul has long been the GOP holy grail. It helped elect President Donald Trump and has driven the Republican agenda in Congress, given GOP office-seekers a rationale for their candidacies and fuelled countless fundraising appeals.

Yet Republicans have never rallied behind an alternative and spent years settling for dozens of bills scuttling the law that went nowhere. Now, with a GOP president and party control of the House and Senate, voters expect Republicans to deliver and party leaders are banking on it.

“If you’re a Republican who votes against ‘Obamacare’ repeal, you’re going to have a lot of explaining to do to your constituents,” said Doug Badger, a GOP health care adviser.

There are few hard-line conservatives on the two committees poised to vote this week, so the panels will likely approve the legislation over unified Democratic opposition.

Rockier problems loom in the full House and Senate. If 22 House Republicans or three Senate Republicans join united Democrats and oppose health legislation, it would fail.

Highlighting an unabated push to influence the legislation, some GOP governors asked lawmakers last weekend to let states choose to continue receiving unlimited federal money to treat all who qualify for Medicaid, according to documents obtained by The Associated Press. Currently, the GOP bill would instead give states set amounts for each Medicaid recipient — a pathway to gradually cutting the federal-state health programme for the poor.

It seems counterintuitive that Congress’ conservatives would derail such a major, early priority for Trump and GOP congressional leaders. But they have the numbers and anti-establishment temperament to do just that.

Many in the hard-right House Freedom Caucus, which claims around 40 members, oppose the GOP bill’s proposal for tax credits to help pay medical expenses for people not covered at work or through the government. They object that the credit, geared to age not income, would even go to people who owe no taxes.

They also oppose a proposal by House Speaker Paul Ryan, Republican from Wisconsin, to tax part of the value of expensive employer-provided coverage. That’s an abomination for many Republicans, aware that about half of Americans get health insurance at work.

“A new plan that actually taxes the very workers that voted for Donald Trump and voted for many of our members is not moving in the right direction,” said Representative Mark Meadows, Republican from North Carolina, who chairs the caucus and says the bill lacks the votes to pass.

Across the Capitol, the magic number of three conservative GOP senators — Ted Cruz of Texas, Rand Paul of Kentucky and Utah’s Mike Lee — are causing headaches. They want the GOP to start with a bill Obama vetoed last year that annulled more of his statute than does the current Republican plan.

Cruz tweeted Friday: “When you spend 6 yrs promising, ‘If only we get elected, we’ll repeal #Obamacare,’ you can’t renege,”

Conservatives want Republicans to quickly repeal Obama’s expansion of Medicaid to more lower-income people, complaining that the GOP leaders’ measure does that too slowly. There’s also a battle between GOP-run states that accepted federal money to expand Medicaid and Republican-dominated states that didn’t expand but want extra funds anyway.

The legislation remained a work in progress over the weekend, but the plans would repeal the tax penalties Obama’s statute impose on people who don’t buy insurance and end the federal subsidies most get for purchasing policies on the online exchanges the law created. Taxes on higher-income people, the insurance industry and other health industries that pay for the overhaul’s expansion of coverage to 20 million Americans would be voided.

The measure would expand tax-advantaged health savings accounts and end the overhaul’s requirement that insurers cover 10 specific types of care, like maternity care.