A grinning Vice President Mike Pence cast a tiebreaking U.S. Senate vote on Thursday, moving one step closer to giving states the power to deny some federal block-grant funds to abortion providers including Planned Parenthood.

With Democrats' mouths agape, Pence came to the Senate chamber to break a 50-50 deadlock on the measure, which ended debate on a move to change how so-called Title X funding is distributed.

The vice president is a staunchly pro-life conservative.

Title X is the only federal grant program 'dedicated solely to providing individuals with comprehensive family planning and related preventive health services,' according to the Department of Health and Human Services.

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Vice President Mike Pence was called to the Senate floor on Thursday to cast a tie-breaking vote that repealed a Health and Human Services rule prohibiting states from withholding 'Title X' block-grant funding from abortion providers

The 50-50 deadlock was tallied after Republicans brought Georgia Sen. Johnny Isakson to the floor despite being in mid-recovery from two back surgeries; Isakson is shown at top right, hobbling with the aid of a walker

A rule passed in the twilight months of the Obama administration denied states the power to withhold funds from any grant recipient meeting that broad definition.

That measure was seen as a carve-out for Planned Parenthood, the nation's largest abortion provider – a small part of whose activities include non-abortion family planning.

The Vice President of the United States has but one constitutional role: as 'president' of the Senate, he can be called on to break ties.

'On this vote the nays are 50, the yeas are 50,' Pence announced Thursday. 'The Senate being equally divided, the Vice President votes in the affirmative and the motion to proceed is agreed to.'

The House of Representatives passed the measure in February and sent it to the Senate for a vote.

With Senate debate ended, a final vote in the afternoon will put the repeal of the Obama-era rule into immediate effect.

Planned Parenthood is America's largest chain of abortion clinics, but it had qualified for Title X funds because it devotes a small part of its activities to contraception services

Nevada Democratic Sen. Catherine Cortez Masto called the Republicans' move 'despicable'

The late-morning vote was a high-stakes government drama, with Senate leaders holding it open for an hour while staffers fetched Georgia Republican Johnny Isakson to force a tiebreaker.

Isakson, recovering from a pair of back surgeries, hobbled to the Senate floor to cast his 'yea.'

Two Republicans, Lisa Murkowski of Alaska and Susan Collins of Maine, voted with the Democrats, making Isakson's participation necessary.

The last time a sitting vice president cast a tiebreaking vote on a piece of legislation was a tax policy vote in 2008, when Dick Cheney created a 51-50 majority.

Pence, however, already had one Senate vote under his belt: He supported Education Secretary Betsy DeVos, breaking a deadlock to confirm her in February.

Democrats were outraged on Thursday, blasting Republicans for politicizing Title X funding.

California Sen. Dianne Feinstein called the move 'shameful,' saying in a statement that '[a]llowing states to defund Planned Parenthood because politicians want to punish a health care provider only hurts women.'

Nevada Democratic Sen. Catherine Cortez Masto called Pence's vote 'despicable' in a tweet.

Patty Murray of the state of Washington spoke after Pence rapped his gavel.

'Republicans didn't listen to us,' she complained. 'They didn't listen to women across the country who made it clear that restricting women's access to the full range of reproductive care is unacceptable.'

'We are not going to give up. we are going to keep holding them accountable, and we are going to keep making sure that women's voices are heard,' Murray said.

The federal government had already largely prohibited Title X money from paying for abortion services. But Planned Parenthood and other clinics have applied for the grants for non-abortion services – with Republicans arguing that the funds can be easily moved around.