"I'll fight every day to make our Republican majority act like one," Blackburn said in a three-minute video announcing her candidacy that was released hours after an establishment favorite -- Gov. Bill Haslam -- said he wouldn't run.
The US Senate, Blackburn says, is "totally dysfunctional and it's enough to drive you nuts."
It's a drastically different diagnosis of Washington's problems than retiring Sen. Bob Corker offered on Wednesday.
Corker told reporters that some in Trump's administration have advocated policies that aren't "sound and coherent." He cast President Donald Trump's Secretary of State Rex Tillerson, Defense Secretary James Mattis and chief of staff John Kelly as the buffers who "help separate our country from chaos
Blackburn, though, is closely aligning herself with Trump -- and against figures like Senate Majority Leader Mitch McConnell.
"I'm a hardcore, card-carrying Tennessee conservative. I'm politically incorrect and proud of it," Blackburn says in the video. "So let me just say it like it is: The fact that our Republican majority in the US Senate can't overturn Obamacare or will not overturn Obamacare -- it's a disgrace. Too many Senate Republicans act like Democrats or worse. And that's what we have to change."
She is also making clear that her campaign will focus on cultural themes.
In the video first reported by The Tennessean
, Blackburn hits several of the contentious debates Trump has inflamed -- saying she stands for the National Anthem, supports Trump's "immigration ban" and will "fight with him every step of the way to build that wall." She also says she carries a gun in her purse and fought against Tennessee imposing a state-level income tax.
"I know the left calls me a wing-nut or a knuckle-dragging conservative," Blackburn says. "And you know what? I say, that's all right, bring it on. I'm 100% pro-life. I fought Planned Parenthood and we stopped the sale of baby body parts, thank God."
Blackburn is likely to get strong backing from outsider GOP forces. Another possible contender and favorite of former Trump White House chief strategist Steve Bannon, state Sen. Mark Green, is now running for Blackburn's House seat
The Tennessee Senate race already included one Republican candidate in Andy Ogles, the former head of Koch brothers-funded Americans For Prosperity's Tennessee chapter. Nashville auto dealer Lee Beaman has said he'll raise $4 million to fund a pro-Ogles super PAC
Another Tennessee Republican who isn't running
: Former University of Tennessee Volunteer and NFL great Peyton Manning.
On the Democratic side, Nashville attorney and Iraq War veteran James Mackler is in the race. Another possible contender, Chattanooga Mayor Andy Berke, has acknowledged he is considering the race
. Democratic strategists had suggested for months the race could become one to watch, as expectations that Corker could retire or face a serious primary challenge.