Rick Santorum speaking during a campaign rally in Madison, Mississippi June 19, 2014. REUTERS/Jonathan Bachman

SHREVEPORT, La. -- Supporters of Rep. Bill Cassidy (R-La.) eagerly filed into a Baptist church here to see the front-running Senate candidate campaign with Rick Santorum Wednesday evening.

But they had to make do with just Santorum, who they welcomed warmly.

Cassidy's campaign announced shortly before the event that he would be absent due to votes in the House.

Santorum, the former presidential candidate, spent much of his speech lambasting President Obama and closely associating Sen. Mary Landrieu (D-La.) with the president's record.

"The only thing that will deter this president ... is you," he told the audience.

Santorum excoriated Obama for taking executive action to stop the deportations of millions of undocumented immigrants.

He praised Cassidy and told the audience they have a chance to send "not just a warning shot, but a torpedo into the side of the destroyer" by electing him to the Senate to replace Landrieu in the runoff.

Cassidy's wife, Laura Cassidy, spoke on her husband's behalf, telling attendees: "We need your prayers and we need your vote."

She warned that the "Obama-Landrieu turnout machine" will be activated in Saturday's vote.

Laura Cassidy also led the crowd to repeat an oft-used taking point -- that Landrieu has voted with Obama "97 percent" of the time.

In Washington on Wednesday, the House overwhelmingly approved a bill that would allow people with disabilities to establish tax-free savings accounts to pay for housing, education or some medical expenses. The accounts wouldn't count against potential Medicaid or Social Security benefits.

Cassidy's absence here spurred criticism from the Landrieu campaign, which accused him of dodging questions about his record as a part-time physician and teacher at Louisiana State University.

"There should be no question that Bill Cassidy is hiding from Louisiana voters," said Landrieu spokesman Fabien Levy in a statement.

Landrieu has repeatedly suggested Cassidy may have committed payroll fraud ever since a local blog revealed the details of some of his timesheets, prompting LSU to look into the matter.

Cassidy's campaign said he will campaign with senator-elect Joni Ernst (R-Iowa) on Friday.

Santorum is considering running for president again in 2016. He said he is "not making any announcements" about his plans right now.

Ed O'Keefe contributed to this post.