Story highlights Republicans need the backing of at least 50 of their 52 members to repeal Obamacare

There are at least two pro-choice senators who caucus with the GOP

Washington (CNN) A push by Republican congressional leaders to defund Planned Parenthood could threaten passage of their top-priority legislation to repeal Obamacare because of opposition to the anti-abortion provision by two key GOP senators.

House Speaker Paul Ryan announced Thursday that Republicans will move to strip all federal funding for Planned Parenthood as part of the process they are using early this year to dismantle Obamacare.

Congressional Republicans have tried for years to zero out all federal funding for Planned Parenthood because the group provides abortion services. The fight over Obamacare helped trigger a 16-day government shutdown in 2013, and Democrats and President Barack Obama insisted any Planned Parenthood provision targeting the group be removed from a bill to fund federal agencies.

The decision to add the controversial Planned Parenthood language, which is opposed by most Democrats, could have a major impact on getting the Affordable Care Act repeal legislation through the Senate because supporters need the backing of at least 50 of their 52 members and two pro-choice senators, Susan Collins of Maine and Lisa Murkowski of Alaska, won't commit to approving the bill with the Planned Parenthood provision in it.

Further complicating matters for Senate GOP leaders is Sen. Rand Paul, R-Kentucky, who announced this week he plans to vote against the Obamacare repeal legislation because the underlying budget measure it is attached to doesn't balance and adds to the deficit. If Murkowski, Collins and Paul all voted against the budget bill, it would be enough to torpedo the Obamacare repeal legislation.

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