Daniels was one of the few high-profile Republican leaders who had not endorsed the former Massachusetts governor, USA Today reported. Romney's support has picked up since former U.S. Sen. Rick Santorum, R-Pa., effectively ended his campaign last week.
A fiscal conservative who was considered a possible presidential contender himself, Daniels said Romney is the best candidate to extricate the country from "ruinous debts and anti-enterprise policies."
Conservative House members urged Romney to open lines of communication with them in the coming weeks, with some indicating they were more passionate about beating President Obama over their party's likely nominee, The Hill reported Tuesday.
Rep. Pete Sessions, R-Texas, chairman of the House GOP's campaign to keep the majority, told The Hill he didn't think a lack of enthusiasm among conservatives would make Romney a liability.
"Mitt Romney as the nominee will enjoy much more support than he did in a competitive Republican primary," Sessions said.
The Hill said it discussed Romney's likely nomination with a dozen House conservatives.
"I would say first, we're excited about the opportunity to defeat Barack Obama more than anything," Rep. Jim Jordan, R-Ohio, chairman of the conservative Republican Study Committee, said. "I think Gov. Romney is the nominee, and you're going to see conservatives unite behind him and do everything we can to help him win this November."
Rep. Louie Gohmert, R-Texas, raised eyebrows when he cracked a joke that referenced Romney's reputation for flip-flopping on issues, The Hill said.
"Let me just tell you: If you're not sure about wanting to support Mitt Romney, whether you're liberal, whether you're very conservative, you ought to be excited, because he's been on your side at one time or another," Gohmert said, later clarifying he would support Romney.
Rep. Mick Mulvaney, R-S.C., defended Romney, saying he would "do what everybody at this table wants to do, which is repeal Obamacare [healthcare reform]. He's going to help us balance the budget sooner rather than later. This is what we've been waiting for."
Rep. Raul Labrador, R-Idaho, who helped organize the event, urged Romney to solicit help from House members who rode the wave of the Tea Party movement into office, The Hill said.
"He needs to reach out to every one of us who's sitting at this table and to all the other conservative leaders throughout the United States," Rhodes said. "Because that's how he's going to win. … And we can help him with that, but he needs to make sure that he reaches out to us."