The Senate Tea Party Caucus met for the first time Thursday as Sen. Jim DeMint (R-S.C.) rebuffed the notion that the caucus would lead to Washington insiders co-opting the grassroots movement. 

"It's not going to be a caucus run by politicians," DeMint told reporters before the start of the group's first official meeting on Capitol Hill. "It's not going to be a sit-down caucus like the Steering Committee that's institutionalized. It's more of a forum than a caucus." 

The group has only four members at the moment — Sens. DeMint, Rand PaulRand PaulGOP rep: Trump has 'extra-constitutional' view of presidency The ignored question: What does the future Republican Party look like? Rand Paul skeptical about Romney as secretary of State MORE (R-Ky.), Mike LeeMike LeeOvernight Healthcare: Medical cures bill finally heads to White House Overnight Energy: Trump taps EPA foe to head agency | Energy reform bill officially dead Senate GOP: National museum should include Clarence Thomas MORE (R-Utah) and Jerry MoranJerry MoranSenate GOP to Obama: Stop issuing new rules Overnight Tech: Bill protecting online reviews heads to Obama | New addition to FCC transition team | Record Cyber Monday Overnight Finance: Trump expected to pick Steven Mnuchin for Treasury | Budget chair up for grabs | Trump team gets deal on Carrier jobs MORE (R-Kansas).

The South Carolina Republican downplayed the group's small membership, saying getting a large number of senators to join isn't the point. 

"What we want to try to do is make [activists] feel like they're part of what's going on," DeMint said. "Remind them that we're listening; we didn't just get elected and forget about them." 

"None of us purports to speak for the Tea Party movement," stressed Lee, who called the Tea Party a "spontaneous, nationwide grassroots political phenomenon."  

Paul said it was the Tea Party that is "co-opting" Washington and not the other way around.

Notably absent was Sen. Marco RubioMarco RubioWhat the 2016 election can tell us about 2018 midterms Fight over water bill heats up in Senate Brown-Mandel Ohio Senate race will be brutal referendum on Trumpism MORE (R-Fla.), an original Tea Party star who criticized the caucus earlier this week, saying in an interview he doesn't see the need for it and doesn't plan on joining.

"My concern is that politicians all of a sudden start co-opting the mantle of the Tea Party," Rubio said Monday. "If all of a sudden being in the Tea Party is not something that is happening in Main Street, but rather something that's happening in Washington, D.C., the Tea Party all of a sudden becomes some sort of movement run by politicians." 

Asked about Rubio's absence, DeMint said he's not concerned.

"That wasn't the whole point," he said. "We didn't try to get everybody here ... Let's just get it started and see what happens."

At least two other newly elected GOP senators spoke at the meeting — Sens. Pat Toomey (R-Pa.) and Jerry Moran (R-Kan). Toomey has not joined the caucus yet, but Moran, who was a founding member of the House Tea Party Caucus, said after the meeting he would become the fourth member.

Toomey came to speak about his bill to prioritize interest payments on debt, which he said would prevent the government from defaulting on its obligations even if the debt ceiling isn't raised this spring. Toomey slammed the argument put forth by Treasury Secretary Timothy Geithner and the Obama administration that not raising the debt ceiling means automatically defaulting.  

"It is factually untrue and very unhelpful to propagate this myth," he said.

Toomey, Paul, DeMint and Lee offered support to the notion that Republicans should tie a constitutional balanced-budget amendment to any vote to raise the debt ceiling.   

Other prominent conservatives and activists in attendance Thursday included Americans for Tax Reform President Grover Norquist, Tea Party Express Chairman Amy Kremer and FreedomWorks President Matt Kibbe. 

—This story was updated at 1:27 p.m. and 5:13 p.m.

An earlier version incorrectly stated Sen. Ron JohnsonRon JohnsonOvernight Regulation: Obama's reg czar under pressure | Fight looms over Trump EPA pick Obama's regulatory czar under pressure to cutoff 'midnight rules' Week ahead: GOP quickly laying groundwork for reg rollback MORE (R-Wis.) is a member of the Tea Party caucus.