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House Speaker Paul Ryan said Thursday that a measure stripping funds from Planned Parenthood would be included in the bill to repeal the Affordable Care Act.

House Republicans’ decision to tie defunding the women's health organization to the Obamacare repeal effort could turn off moderate Republicans, complicating the fragile coalition that the party must maintain in order to undo the massive health care law.

One such Republican, Senator Susan Collins, R-Maine, has already voiced concern. While she said it’s “really premature” to say if she’d vote against a repeal defunding Planned Parenthood, she did say she would fight to strip such a measure from the bill.

"There's a group of House Republicans led by (Rep.) Charlie Dent (R-PA) who are opposed to the defunding of Planned Parenthood in the bill, and I hope they'll be successful in separating the two issues or knocking it out all together,” Collins told reporters Thursday.

Collins voted against the last major effort to repeal the ACA, also referred to as Obamacare, in 2015 in part because Planned Parenthood defunding was included. Sen. Mark Kirk of Illinois took the same stance but he was defeated in his re-election bid last year. Sen. Lisa Murkowski, R-Alaska, opposed previous efforts to strip money from the organization, as well, and could be a critical vote.

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But Collins might see more support from moderate Republicans this year because any repeal effort that passes is likely to be signed by incoming President Donald Trump. Repeal of Obamacare is only going to need the support of a simple majority of senators. With 52 Republican senators, only three need to defect.

House Republicans, who enjoy a much larger majority, must also take Republican defections into consideration. There is already concern among conservative Republicans over the timeline for replacement and that not all tax increases that are part of the ACA, such as the tax on medical devices and the tax on high cost health insurance plans, will be repealed, also threatening Republican repeal efforts.

Not funding $500 million per year for Planned Parenthood would give the GOP some much needed cash to pay for their healthcare replacement while also satisfying the socially conservative portion of their base.

Related: Replacing Obamacare Will be Difficult, Repealing it Will be Just as Hard

A group of Senate Democrats hastily convened a news conference to respond to the Ryan’s pronouncement.

“This is outrageous,” said Sen. Patty Murray, D-Washington. “We are going to fight back every step of the way.”

The vast majority of Planned Parenthood's services revolve around women’s health care, including cancer screening, maternity care and preventative care. The government provides approximately half of the national organization's money — a little more than $500 million dollars per year — but that money does not go to fund abortions, complying with federal law that outlaws the federal funding of abortion.

Ryan’s announcement comes the day after Vice President-elect Mike Pence traveled to the hill to rally Congressional Republicans around the repeal of Obamacare. Pence has been an outspoken opponent of Planned Parenthood, and under his leadership, the state of Indiana drastically reduced the organization's resources, forcing clinic closures such as one that reportedly led to a massive STD outbreak.

During his campaign, President-elect Donald Trump offered mixed messages about Planned Parenthood. He defended the organization several times, saying it has done “very good work for women.” But he also said he would defund it “because of the abortion factor.”

Murray called on Trump to use his Twitter megaphone on the issue.

“I would ask the president-elect to Twitter very loudly tomorrow morning — when he does this — that he stands behind women and that he wants the House to back him,” Murray said.