Republican U.S. Sen. John McCain told a group of veterans gathered at the USS Kidd in Baton Rouge on Monday that he believes GOP Senate candidate Bill Cassidy will better serve Louisiana and veterans’ interests compared to incumbent U.S. Sen. Mary Landrieu.

“I’m here because I believe in Bill Cassidy,” McCain, R-Ariz., told the crowd, many of them dressed in attire and medals marking their military service, during one of several stops the former GOP presidential nominee made across the state to stump for Cassidy this week.

A group who supports Landrieu, a three-term Democrat who is locked in a tight, nationally watched race for re-election, set up outside the museum, could be heard yelling “Veterans for Landrieu” even while McCain and Cassidy made their speeches inside.

“Sen. Landrieu has done a wonderful job,” said retired Army Col. Ron Thompson. “She is known as ‘Military Mary’ for a reason.”

McCain spent much of his speech criticizing President Barack Obama’s administration and Democratic control of the Senate.

“We need a leader,” he said. “Someone who understands the challenges.”

He said Cassidy’s background as a doctor will make him a strong voice for veterans in the Senate.

“It is literally a national disgrace that we have neglected our veterans,” McCain said. “I guarantee you when we’re in the majority ... then (Sen.) Mitch McConnell (R-Ky.) is committed to naming him to be one of the leaders in addressing the health care needs of our veterans.”

Asked after his speech about his specific issues with Landrieu, McCain said he thinks she has been ineffective on veterans issues and other efforts, including the proposed Keystone XL pipeline, which Landrieu supports despite delays from the Obama administration.

“She hasn’t done anything in the time I’ve known her,” McCain said. “As a Democrat, she can’t convince (Sen.) Harry Reid (D-Nev.) to bring it to a vote of the Senate, where it would pass. She doesn’t even have any influence in her own party.”

McCain is among the latest in a series of high-profile guests on the campaign trail leading up to the Nov. 4 election, which could directly impact control of the U.S. Senate. A Dec. 6 runoff will be held if no candidate gets more than 50 percent of the vote the first time around.

In addition to Landrieu and Cassidy, Republican Rob Maness, a political newcomer backed by the tea party and retired military colonel, also is in the race, as are some lesser-known candidates.

Cassidy, Landrieu and Maness will participate in a debate in Shreveport on Tuesday.

Other national figures who have campaigned in Louisiana’s Senate race include former President Bill Clinton, who headlined a Landrieu fundraiser in New Orleans last month, and McCain’s vice presidential runningmate Sarah Palin, who has campaigned for Maness.

In a written statement, Landrieu praised the military record of McCain, who was a prisoner of war in Vietnam, but she also took digs at Cassidy in the process.

“It’s a real shame the guy (McCain) is campaigning for can’t find the courage to face the voters of his own state for five one-hour debates,” she said, referencing a series of debates in which Cassidy has declined participation.

Tuesday’s debate at Centenary College is one of two televised debates in which the GOP frontrunner is scheduled to participate.

Landrieu is chairwoman of the Homeland Security Appropriations Subcommittee that funds the Coast Guard, and her campaign claims she has worked to protect and create more than 40,000 military jobs during her nearly two decades in the Senate.

The release from her ticks off several points hailed as evidence of her pro-military bonafides, including support for workforce and health care legislation benefiting veterans.

U.S. Sen. David Vitter, a Louisiana Republican, also participated in the pro-Cassidy veterans event Monday.

“I spend a lot of time with veterans from all across the state,” said Vitter, who is running for governor next year.

He also heavily criticized the Obama administration and sought to tie Landrieu to the president’s politics.

“Leadership — or lack thereof — matters,” Vitter said. “Bill Cassidy is for strong American leadership. There is a very clear choice in this election.”

Cassidy took several photos with attendees, who lined up to greet him after his speech, while shouts from “Veterans for Landrieu” continued to ring out from across the street.

“I’m taking on the most powerful man in the world and a senator who has supported him 97 percent of the time,” Cassidy told the crowd. “You win if we win.”

Follow Elizabeth Crisp on Twitter @elizabethcrisp. For more coverage of Louisiana politics, follow our Politics blog at .