U.S. Rep. Tammy Duckworth (D-Illinois) will announce a 2016 Senate bid come Monday, the Chicago Sun-Times reported Friday afternoon.
Duckworth's campaign did not immediately respond to The Huffington Post's request for comment.
Just a day earlier the paper obtained a fundraising letter from Duckworth, asking supporters for $1,000 donations so she could mount a bid against Republican Sen. Mark Kirk.
“My gut tells me I can beat these guys,” Duckworth wrote, according to the Sun-Times.
A former helicopter pilot, Duckworth became the first female Iraq combat veteran in Congress when she joined the House in 2013.
Kirk's seat is considered among the GOP's most vulnerable heading into the 2016 races. In January he responded to the news that Duckworth was mulling a Senate run, telling Politico he did not consider the Congresswoman a threat.
“It’s going to be a vigorous campaign that I will overwhelmingly be likely to prevail in,” Kirk said. “I’ve always had tough races in the House and Senate, and I’ve beat everybody.”