House Speaker Paul Ryan. Win McNamee/Getty Images The House Freedom Caucus, a conservative wing of congressional Republicans, voted Monday night to support a swift and aggressive repeal of the Affordable Care Act, complicating GOP efforts to unite around a plan to repeal and replace the healthcare law better known as Obamacare.

According to reports, the Freedom Caucus said it would not back a repeal if it did not include all of the elements of a repeal bill that debuted in 2015. It also said it wanted to quickly repeal the law, even if no replacement bill was ready.

The 2015 repeal bill, which was passed by the GOP in Congress but vetoed by President Barack Obama, included repeals of the individual mandate, the Medicaid expansion, and the taxes to fund premium subsidies that aid people in paying for coverage.

Republicans had already been drafting a repeal bill via budget resolution that would allow them to repeal any part of the ACA that involves the federal budget.

But the vote by the Freedom Caucus could complicate the timeline of a repeal-and-replace plan. Disagreements over which elements to repeal and which to include in a second overhaul bill may make a cohesive vote from Republicans harder to come by.

Some more moderate lawmakers have softened their approach and considered keeping some of the ACA's provisions as part of the repeal. Even in some deeply red states, GOP lawmakers have been bombarded at town halls by constituents who have expressed concerns about the law's repeal.

With Democrats vowing to oppose the changes at every turn, Republicans need to ensure they rally around a single bill to accomplish repeal. According to Politico, the Freedom Caucus said 50 members had signed on to its outlook on the repeal.

Part of the concern from Freedom Caucus members is that not acting swiftly and decisively on a repeal could threaten the long-term success of an overhaul of Obama's healthcare law, with support for the changes potentially losing steam and becoming bogged down in Congress.

By pushing for a fast and total repeal, Freedom Caucus members hope to force moderate Republicans and some Democrats into crafting a replacement.

"It's our hope that in doing so it will bring some others along for a replacement bill once they understand that it has been repealed that you get some Democrats and certainly more moderate Republicans to work in earnest with replacement," Rep. Mark Meadows, a Freedom Caucus member representing North Carolina, told Politico.

Republicans have been considering measures to stabilize the individual markets set up by the ACA to ensure that American with coverage through these exchanges are able to keep it while a replacement is developed. Some GOP members have stressed a need to "repair" the law before they repeal and replace it.

Additionally, numerous Republican governors and lawmakers in states that have expanded Medicaid through the ACA have expressed a desire to keep this aspect of the law to cover more poor families in their state. If a bill similar to the 2015 repeal bill were to be passed, it would end federal funding for that expansion.

Health-policy experts have been concerned that a repeal, or serious steps toward a repeal without a replacement, could lead insurers to leave these markets, potentially destabilizing them and causing large cost increases and coverage lapses. In fact, some large insurers are already questioning their involvement in individual markets next year, given the uncertainty over the GOP plan.

House Speaker Paul Ryan has offered a few timelines on the repeal and replacement of the law. He has said "the legislating" will be done by the end of this year, that it will be done by the end of the summer, and that it will be done by the end of the first quarter of the year.

Even with the statement by conservative members of the House, the timeline for the repeal remains unclear.