Pennsylvania Republican Dave McCormick officially kicked off his 2024 US Senate campaign at a rally in Pittsburgh Thursday evening, castigating incumbent Democratic Sen. Bob Casey as President Joe Biden's "rubber stamp" and saying that "both parties need to be shaken up."

"Today, I'm announcing my candidacy for the United States Senate," the former hedge fund CEO told a cheering crowd, delivering a focused speech filled with criticism of the Biden administration and repeated efforts to tie Casey to the president.

McCormick enters this race as the front-runner for the Republican nomination and, according to GOP donors and officials, is expected to be a formidable challenger to Casey, who won a third term in 2018 with more than 55% of the vote.

Last year, McCormick attempted to secure the GOP nomination for the state's other Senate seat but lost to television doctor Mehmet Oz, who went on to lose the general election to Lt. Gov. John Fetterman, expanding Democrats' majority in the Senate.

McCormick referenced that record in his speech, saying, "I know what it's like to lose a big match and walk off the mat. And I know what it's like to get fired from a job. And I know what it's like to lose a big election -- you may have heard something about that. But each and every time, I picked myself up. I dusted myself off."

Speculation that McCormick would run again began shortly after his last campaign had officially ended. In late May, McCormick announced that he was "seriously considering a run" in a statement released shortly after Pennsylvania state Sen. Doug Mastriano, a fervent election denier and the losing 2022 GOP nominee for governor, said he would not enter the contest.

During Thursday speech, McCormick seemed to signal his intent to run a campaign with broader, bipartisan appeal -- he vowed to "earn the votes of all citizens of this great commonwealth, regardless of their party." He made no mention of the culture war clashes that have animated many Republican campaigns in recent cycles.

Throughout the speech, McCormick repeatedly tied Casey to Biden, and argued that the senator has been in Washington, DC, too long.

"He's Joe Biden's rubber stamp. When Joe Biden says jump, Bob Casey says, how high? When Joe Biden says vote, Bob Casey says, which way? When Joe Biden comes calling, Bob Casey comes running," he said. "Now here's the problem with rubber stamps -- rubber stamps leave the southern border open, right? Rubber stamps expose the people of this commonwealth to rising crime, and a fentanyl crisis. Rubber stamps vote for trillions of dollars of spending, like Senator Bob Casey did when he voted for the Biden Inflation Creation Act. "

With Democrats holding a narrow Senate majority, defending seats like Casey's will be key to the party maintaining control of the chamber. Democrats hold most of the competitive Senate seats on the ballot next year, including six in states that have voted for Trump at least once, Pennsylvania being one of them.

Casey -- who is not expected to face a serious challenge in the Democratic primary -- announced his reelection campaign in April. The son of a former governor, he has long been a fixture in Pennsylvania politics, previously serving as state auditor general and treasurer.

Pennsylvania is currently scheduled to hold primary elections on April 23, but state lawmakers are looking to change the date to avoid a conflict with Passover.