A Democratic lawmaker from Pittsburgh resigned Wednesday from the Pennsylvania House of Representatives, moving the razor-thin majority her party has held this year to a partisan tie with the Legislature mired in a budget stalemate.

Democratic Speaker Joanna McClinton immediately scheduled a special election for Rep. Sara Innamorato's Allegheny County seat for Sept. 19, a week before the House is expected to return to session.

In November, Democrats flipped the number of districts needed to control the House at the start of the session. It was their first claim to the majority in 12 years, with a 102-101 margin they have since maintained through several special elections.

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With Innamorato's resignation, the partisan breakdown now sits at 101-101.

A text message seeking comment was left for Innamorato.

House Republican spokesman Jason Gottesman described her resignation as an effort by Democrats to "gerrymander the membership of the House" to maintain their power. He said it would have a significant impact on resolving the budget negotiations.

Democrats have used their newfound power this year to advance a number of the caucus’ priorities, from gun control efforts to broader protections for LGBTQ+ people. But the Legislature remains politically divided, with a firm Republican majority in the Senate.

Her departure makes it more difficult for Democrats to advance measures on party-line votes.

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The philosophical divide in the Legislature turned especially unyielding this month; the state government has gone for weeks without full spending authority due to a battle over education funding that has soured budget negotiations. The stalemate could persist until the chambers return to business after Labor Day.

Innamorato is running to serve as the Allegheny’s county executive. She won a contested Democratic primary for the race in May, as part of a progressive slate in local elections. She’ll face the lone Republican primary contender, Joseph Rockey, in the November general election.

Another Democratic Rep. John Galloway, of Bucks County, is running for district judge, meaning the Democrats will face another race with the majority at stake.