BATON ROUGE (AP) — Republican U.S. Rep. Bill Cassidy is running for the Senate next year, seeking to keep Democratic U.S. Sen. Mary Landrieu from a fourth term in office.

Cassidy, a Baton Rouge doctor elected to Congress in 2008, will release a video Wednesday announcing his candidacy.

The video was provided to The Associated Press by someone associated with the Cassidy campaign who asked not to be identified because the announcement had not been made public.

In the announcement, Cassidy describes Landrieu as too close politically to President Barack Obama, who remains unpopular in Louisiana.

“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. 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,” Cassidy says, sitting with his wife, Laura.

Cassidy, a former state senator, is the first Republican to declare his intention to run for the Senate seat, a move that could determine whether other GOP contenders decide to jump in the race.

Landrieu, a moderate Democrat who won 52 percent of the vote in 2008, has been considered vulnerable each time she’s been up for re-election because Louisiana is a red state in national elections. Last year, Republican Mitt Romney defeated Obama in Louisiana by 17 percentage points.

In his video, Cassidy and his wife describe their medical careers, their three children and work in their local community. The congressman talks of his opposition to Obama’s health care overhaul, his support of gun rights and his anti-abortion stance.

“President Obama does not want me, a conservative Republican, representing the views of the people of Louisiana, to serve in the Senate,” Cassidy says.

He also repeatedly ties Landrieu to the Democratic president, saying Louisiana’s senior senator supports Obama 97 percent of the time and was a deciding vote in passage of the federal health care law.

“Now Mary’s a nice person, but she’s changed,” Cassidy says in the video.

Landrieu didn’t comment Tuesday on Cassidy’s planned announcement.

The Louisiana Democratic Party issued a statement criticizing Cassidy as “fighting for extremists in Washington and repeatedly voting against the people of Louisiana,” saying the congressman voted against hurricane recovery funding and supported budget policies that would harm middle class families.

Cassidy won re-election in the fall with 79 percent of the vote to return to the 6th District seat representing Baton Rouge and several other southeastern Louisiana parishes.

Other Republicans are reportedly eyeing the Senate race as well, including Cassidy’s colleague, U.S. Rep. John Fleming, a doctor from Minden who has issued a flurry of news releases in recent weeks attacking Landrieu’s votes in the Senate.

Cassidy’s announcement didn’t immediately persuade Fleming to take himself out of consideration.

“I haven’t ruled anything out. The polling I’ve done has made it clear that a conservative Republican can defeat Mary Landrieu. So, whether it’s Bill or I, the critical issue is that Louisianians have a distinct choice,” Fleming said in a statement.

Also mentioned as possible GOP candidates include former U.S. Rep. Jeff Landry of New Iberia and state education board president Chas Roemer.