(Bloomberg) --The Senate parliamentarian told lawmakers that Republicans’ ability to pass an Obamacare replacement with just 51 votes expires at the end of this month, Senator Bernie Sanders said Friday.

The preliminary finding complicates any further efforts by Republican leaders in Congress to pass a comprehensive GOP-only replacement for the health-care law.

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Sanders, a Vermont independent, in a statement called the determination a "major victory" for those who oppose repealing Obamacare.

Senate Republicans, who control the chamber 52-48, failed to win enough support for their Obamacare replacement in July as three GOP lawmakers joined Democrats to oppose the measure. Republican leaders haven’t ruled out reviving their effort, and some party members -- including Lindsey Graham of South Carolina, Bill Cassidy of Louisiana and Ted Cruz of Texas -- say they’re talking to colleagues about a possible broad-based bill.

At the same time, some senators are discussing a scaled-back, bipartisan health measure. It takes 60 votes to overcome a Democratic filibuster, and Democrats are united against a full replacement of Obamacare.

The Senate Health committee has scheduled four hearings this month to examine bolstering Obamacare’s insurance exchanges after a number of insurers exited regional markets in Missouri, Iowa, Tennessee and other states. Chairman Lamar Alexander, a Tennessee Republican, and the panel’s top Democrat, Patty Murray of Washington, have pledged a bipartisan effort to shore up the exchanges, which provide consumers a place to purchase individual coverage.

Earlier guidance from Senate Parliamentarian Elizabeth MacDonough dogged Republicans in their Obamacare replacement effort throughout the summer. In late July, she issued a preliminary finding that key parts of a proposal drafted by Senate Majority Leader Mitch McConnell didn’t qualify for the fast-track procedure, dramatically complicating the already slimming prospects of passing a bill.

The parliamentarian’s new finding doesn’t preclude Republicans in both chambers from seeking to restore the ability to use a 51-vote majority for an Obamacare repeal in the next fiscal year that starts Oct. 1.

The House Budget Committee has drafted a fiscal 2018 budget that could be used for both Obamacare repeal and tax reform. That budget may come to the floor in mid-September, and the Senate Budget Committee hopes to release its version in the coming weeks. Still, doing a tax overhaul and Obamacare repeal in the same legislation would be time-consuming and unlikely.

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