Democratic U.S. Sen. Mary Landrieu and Republican challenger Rob Maness squared off on issues related to wetlands, energy policy and busting through the partisan gridlock in Washington, D.C., in front of a packed crowd at Kenner City Hall on Tuesday night, but the leading GOP candidate, Bill Cassidy, wasn’t in attendance.

State Rep. Paul Hollis, R-Covington, said Cassidy, a Baton Rouge Republican, personally asked him to sit in his place. Hollis said U.S. Rep. Cassidy had a prior engagement and couldn’t make it to the Alliance for Good Government Forum.

During the nearly 45-minute discussion, Maness and Landrieu outlined their views on oil exportation, Medicaid expansion and President Barack Obama’s decision to authorize airstrikes against the Islamic State group.

The federal Affordable Care Act position showed the clearest distinction between longtime Democrat Landrieu and tea party-backed Maness, and it drew the largest response from the crowd, whose reaction seemed mixed.

Landrieu said she supports expansion of Medicaid and that the state’s decision not to support it has had a negative impact on Louisiana residents.

“It left 15,000 jobs that were not created, and it left $16 billion of our tax dollars on the table,” she said.

Maness said he thinks that the federal Affordable Care Act needs to be “pulled out by the roots” and he doesn’t support expansion.

Both Maness and Landrieu pledged to work across party lines on issues that would benefit the state.

“We must come together for solutions,” Maness said, adding his status as a political novice makes him a better option for the Senate.

“We have a choice in this election — your choice is to go with one of the politicians or an outsider,” Maness said.

Landrieu said she has been building coalitions with Republicans throughout her time in the Senate, notably when it came to flood insurance rates. “I’m willing to cross party lines to get the job done for this state,” she said.

Maness, a retired military colonel, said he believes Obama overstepped his bounds by taking action against the Islamic State group without congressional approval.

“Congress should be going back into session to debate why and what we are going to war for, instead of giving this president a blank check,” said Maness, though he called the Islamic State group an “imminent threat.”

Landrieu, agreeing that the Islamic State group poses a “serious threat,” said she would vote in favor of airstrikes and other actions against the Islamic State group, had Obama sought congressional approval.

During an introduction and closing, Hollis touted Cassidy’s congressional record.

“Bill Cassidy has been a stalwart opponent to President Barack Obama,” Hollis said. “He has fought for the rights of people of Louisiana and I know he will continue in the United States Senate.”

Landrieu and Maness criticized Cassidy for not attending the forum, repeatedly thanking each other for showing up.

Both have been quick to bring up Cassidy’s decision to participate in just two televised debates — one on Oct. 14 and the other Oct. 29.

“You can talk about everything you’d like to do and what you’d stand for, but the first thing you have to do is show up,” Landrieu said.

Earlier Tuesday, Landrieu met with several dozen college students from LSU, Baton Rouge Community College and Southern University in Baton Rouge. She’ll be in New Orleans for similar meetings Wednesday, and next week she’ll hold a meeting in Shreveport.

Landrieu touted her efforts to address student loan debt and increase the amounts of federal Pell Grants — two points she has repeatedly stressed to college students on the campaign trail.

“It’s about building a path to the middle class,” she said, stressing that Louisiana needs a skilled workforce to meet industry demands.

In response, Republican National Committee spokesman Ben Voelkel shifted the focus back to the economy.

“What students need is not more student loans — they need good jobs available to them when they graduate,” he said. “Unfortunately, Senator Landrieu’s rubber stamp support for President Obama’s agenda has failed young people who now face high unemployment rates, stagnating wages and fewer opportunities than generations before them.”

Landrieu also again talked up her “clout” in Washington as a three-term senator — another point the GOP has taken issue with.

“Why would we want to give this up?” Landrieu asked the room full of students. “Why would we want to concede this power and seniority to another state?”

Follow Elizabeth Crisp on Twitter, @elizabethcrisp. For more coverage of the Louisiana Legislature, follow our Politics blog at http://blogs.theadvocate.com/politicsblog .