EMILY’s List, an influential group working to elect pro-abortion rights female Democrats to Congress, on Thursday endorsed Alex Sink for the House seat vacated earlier this month by the death of Rep. Bill Young (R-Fla.).

Sink announced her campaign on Wednesday, giving Democrats a serious shot at picking up a seat in a solidly Republican district that had been represented by Young for more than four decades.  

EMILY’s List’s endorsement of Sink solidifies the former candidate for Florida governor as the top Democratic contender in the race, but creates tension within the party. Sink will run against St Petersburg lawyer Jessica Ehrlich in the Democratic primary.

Before Sink entered the race, EMILY’s List had already named Ehrlich “On the List” – in other words, one of the group’s top recruits. But the group also supported Sink in her 2010 gubernatorial bid against Republican Gov. Rick Scott.

The group’s sudden shift to back Sink signals that Ehrlich may be pushed out of the race.

“Alex Sink has an outstanding record of public service and business leadership, and she’ll be ready to use her experience to fight for Florida in Congress from the day she takes office,” said Stephanie Schriock, President of EMILY’s List, according to a press release.

“The EMILY’s List community – now more than two million members strong – is excited to have the opportunity to help Alex Sink become the first Democratic woman to represent Florida’s 13th Congressional District.”

Scott this week set the dates for the special elections to fill the late Republican’s seat: The primary will be held on Jan. 14 and the general election will be on March 11.