(CNN) The days of swift and decisive Obamacare repeal are long gone.

Not a month into Donald Trump's presidency, Republican leaders in Congress have run up against just about every speed bump imaginable in their quest to dismantle the Affordable Care Act.

Deep ideological divisions have burst into the open over how much of the health care law to roll back and how quickly, as well as the fate of Medicaid expansion and federal funding for Planned Parenthood -- all as angry constituents who support Obamacare are hounding GOP lawmakers at town halls across the country.

In Republicans' telling, it was never supposed to be this difficult: No other issue has been more potent in uniting the party and galvanizing its base than gutting Obamacare, and GOP lawmakers kicked off the new Congress with a fresh thirst to exercise their newly gained power in Washington and kill the health care law once and for all.

Here are the major sticking points that have Republicans struggling on Obamacare repeal:

Conservatives hold the line on repeal

The House Freedom Caucus, a group of conservative lawmakers, want Obamacare repealed -- and they're unhappy it's taken this long.

They signaled to party leaders this week that there's no excuse for the party to delay a repeal vote, and that any repeal bill that's less aggressive than what the GOP approved in the past is simply unacceptable.

"Our simple message is: We don't want to have 'Obamacare light.' That would be a mistake," GOP Rep. Mark Sanford of South Carolina told CNN on Tuesday.

GOP Sen. Rand Paul of Kentucky, who has partnered with Sanford on a replacement bill, said conservatives adamantly oppose the notion of "keep part of Obamacare."

"Most of the conservatives are saying we ought to repeal the whole thing," Paul told CNN. "We did it once in 2015. That's what we feel like we ought to be voting on."

What gets replaced?

Republicans moved quickly last month to begin the process of repealing Obamacare. But before long, rank-and-file members started to ring the alarm bell, arguing that things were moving too fast.

Repealing the sweeping health care law in the absence of a replacement plan, lawmakers said, would be a huge political liability for Republicans and constituents would blame the party for any disruptions or loss in coverage.

To quell the widespread concerns, GOP leaders committed to simultaneously "repeal and replace" parts of the law, and got to work on inserting replacement measures into the repeal package. They've also said the replacement would happen in stages.

"A lot of the delay we're seeing now is based on a disagreement over what elements of replace get included in the bill," said Dan Holler, vice president of government relations at Heritage Action for America. "Because you have to build consensus over what those things are ... all of that takes a little time."

Trump, always the wildcard

Trump has not made the Obamacare deliberations any easier -- in fact, he often adds to the confusion.

More than once, Republican lawmakers and aides have had to scramble to interpret or explain the President's unexpected comments about Obamacare . Last month, Trump puzzled lawmakers and reporters alike when he demanded that his party vote as quickly as the next week to repeal and replace Obamacare, despite Republicans being nowhere close to a finished product.

Days later, Trump said he was putting the finishing touches on an Obamacare replacement plan that would provide "insurance for everybody." The comments irked Republicans who felt Trump had strayed from the GOP's talking point of lowering costs, not expanding coverage.

There has also been plenty of confusion about what health care plan Trump himself may be working on -- if he's working on one at all.

Tensions grow at town halls

Angry town halls are back.

Reminiscent of President Barack Obama's first summer in office, constituents are showing up in droves at public forums across the country seven years after Obamacare's enactment, airing concerns about the GOP's efforts to repeal the law.

The chaotic scenes of protesters, disruptions and heightened security have rattled congressional Republicans and made them increasingly wary of potential confrontations.

"You want to take away this coverage -- and have nothing to replace it with! How can I trust you to do anything that's in our interest at all?" one man who gets health insurance through the Affordable Care Act asked GOP Rep. Diane Black at a town hall last week

The coming weekend and next week's recess are likely to produce more clashes, and put further pressure on Republicans to offer reassurances that millions of people won't suddenly lose their coverage.

Medicaid reforms

A major gulf exists between Republicans who hail from states that expanded Medicaid under Obamacare and those who didn't.

There are more than a dozen Republican senators from expansion states and many of them are advocating to make sure that their constituents who benefited from the expansion don't lose coverage. Lawmakers must also take into consideration the 16 Republicans governors who lead states that have expanded -- several are pushing Congress to keep the provision.

The 2015 health care reconciliation bill called for phasing out Medicaid expansion, something that the House Freedom Caucus is now pushing for.

One option being laid out by the House Energy and Commerce Committee is to "freeze" Medicaid expansion -- not kick any one off but not allow new recipients to enroll. The hope is that over time, individuals will move off of Medicaid. To make it fair to states that didn't expand Medicaid, non-expansion states will continue to receive disproportionate share of payments, which the government pays hospitals for caring for people who don't have insurance.

"We don't want to just stop it, but how do you transition off that's fair to states that didn't expand?" said GOP Rep. Brett Guthrie, the vice chair for the subcommittee on health.

Conservatives have long targeted Medicaid for cuts. Many now want to overhaul the entire entitlement, turning it into a grant program that would provide a fixed level of federal funding to the states but give them more flexibility to run it.

Keep or cut Obamacare taxes?

Obamacare levied a bevy of taxes on higher-income Americans, insurers, employers with generous plans and others.

Some lawmakers want to see these taxes repealed right away, while others argue they are necessary to pay for the new GOP health care system

The latter is simply unacceptable to some Republicans.

"The burdens of the vast majority of these taxes are ultimately borne by patients and consumers in the form of higher costs, larger tax bills and reduced value in existing health plans and savings accounts," Senate Finance Committee Chairman Orrin Hatch said in a statement Wednesday.

But others, including some policy experts at the American Enterprise Institute, say not so fast.

Not only will killing the taxes immediately severely limit the funding for the tax credits Republicans want to use to help people afford coverage, but Congress also needs the money now to continue paying for Obamacare's subsidies and Medicaid expansion during the transition period.

Planned Parenthood funding

Another potential non-starter for conservatives: a failure to defund Planned Parenthood.

Republicans voted in 2015 as a part of the legislation to repeal Obamacare to strip federal funding for the group. This year, some conservatives are beginning to worry that that provision could end up on the chopping block if the party starts to make any concessions on repeal.

"We're also hearing that the defund Planned Parenthood language may not stay in," GOP Rep. Jim Jordan told CNN in a recent interview.

Complicating matters is the fact that at least two pro-abortion rights senators across the Capitol -- Susan Collins of Maine and Lisa Murkowski of Alaska -- won't commit to supporting an Obamacare repeal bill if a provision to defund Planned Parenthood is included.

Insurance market is jittery

As if that weren't enough, Republicans are getting additional pressure from insurance companies. Their message to Congress: The clock is ticking.

Humana announced this week that it is pulling out of Obamacare for 2018, becoming the first major insurer to exit the Affordable Care Act exchanges under Trump. Others have warned that they could be next to go: Obamacare is in a "death spiral" and more insurers will flee in 2018, Aetna CEO Mark Bertolini warned on Wednesday

This leaves Republicans with the tough task of reassuring insurance companies that Congress has a path forward on Obamacare. Insurers have to begin filing their 2018 plans and premiums in April.

For now, Republicans are pointing to the Humana move as proof of Obamacare's fatal flaws.

GOP Rep. Kevin Brady, the Chairman of the Ways and Means Committee, said Humana's exit is "another example of how Obamacare is not just sick -- it is in serious, serious trouble."

Republican Sen. John Barrasso pushed back on the suggestion that insurance companies are nervous because of the uncertainty created by GOP lawmakers.

"This is all the Democrats' problem. They voted for this disaster, it continues to collapse. This is their problem," Barrasso told CNN. "We're trying to repair the problem."