WASHINGTON — U.S. Rep. Bill Cassidy, of Baton Rouge, officially announces his plans to run for the U.S. Senate next year in a video being publicly released Wednesday.

Cassidy’s bid to unseat Democratic Sen. Mary Landrieu, a top target for the GOP nationally, makes him the first Republican to formally announce his foray into the 2014 election.

The video was leaked early to The Associated Press by someone associated with the Cassidy campaign. His campaign officials refused to release the video early to The Advocate.

“As a family, we have decided that I will run for the United States Senate in the election held November 2014, and it’s going to be a tough race,” Cassidy reportedly said in the video. “I’m running against Sen. Mary Landrieu, who’s been there for 18 years, and against the most powerful man in the world, Barack Obama.”

When reached on his cellphone later in the day, Cassidy called the decision a “huge step” for him, but he declined to discuss any other specifics preemptively. “It’s obviously an open secret,” he said.

Cassidy, 55, is a physician and former state senator who first entered Congress in January 2009.

U.S. Rep. John Fleming, R-Minden, who also is a doctor, is seriously considering running for the Senate too. Former U.S. Rep. Jeff Landry, R-New Iberia, and state Board of Elementary and Secondary Education President Chas Roemer also have said they are considering it.

Fleming declined an interview request Tuesday, but he responded in a prepared statement that he has not “ruled anything out.”

Fleming and Cassidy have both spent time attacking Landrieu recently as they battle for leverage as the top GOP contender to the three-term Democratic senator.

Fleming has put out six news releases criticizing Landrieu in the past 12 days.

Landrieu also declined an interview request Tuesday.

But Louisiana Democratic Party Executive Director Stephen Handwerk released a statement arguing that Cassidy votes against Louisiana’s best interests.

“Bill Cassidy has spent his time in Congress fighting for extremists in Washington at the expense of the people of Louisiana,” Handwerk stated. “He is going to have a hard time convincing people in Louisiana that he has their best interests at heart when he repeatedly votes against hurricane protection and recovery funding and votes to give tax cuts to millionaires.”

Cassidy’s announcement comes just after he touted on Monday that he raised more than $500,000 in campaign funds thus far this year, although he still trails Landrieu’s warchest.

Cassidy had a warchest of about $2.4 million as of the end of March. However, Landrieu had $2.53 million in cash on hand at the end of the year and she is expected to have increased that total in the past three months.

Kirby Goidel, a political analyst and director of the LSU Public Policy Research Lab, said he believes Cassidy is announcing early in part to discourage Fleming or any other Republicans from entering the race.

“Ideally, I think the Republican Party is thinking they’d like to unite behind a single candidate and someone who has a lot of money, and I think that’s the Cassidy strategy,” Goidel said. “I don’t know if it’ll work.

“I’d be surprised it he comes out of this without any Republican opposition at all,” Goidel added, noting that Fleming appears the most likely at this point.

Landrieu, on the other hand, wants two or more Republicans “spending a lot of money against each other,” Goidel said.