A handful of Republicans vying to be the next U.S. senator from the state of Iowa will gather on Wednesday night for their first official debate of the campaign. But one potential GOP hopeful who could change the dynamic of the race if he decides to run will be missing

Iowa conservative leader Bob Vander Plaats, who is actively exploring a bid, has been sending more signals recently that he is getting serious.

Vander Plaats, who heads the Iowa-based group, the Family Leader, traveled to Washington, DC earlier this month during the three-day Values Voter Summit, an annual Christian conservative event, and took part in extensive meetings with national political operatives about his potential Senate bid.

Those meetings included discussions with media consultants, pollsters and fundraisers, according to a source familiar with Vander Plaats' deliberations. Topics of discussion included a potential budget for a campaign, an analysis of the Iowa media landscape and specifics about his path to winning the GOP nomination.

Five Republicans are already vying for the chance to take on Rep. Bruce Braley, D-Iowa, who is hoping to keep the seat being vacated by retiring Sen. Tom Harkin in Democratic hands.

But as one Republican operative familiar with Iowa's political terrain told ABC News, should Vander Plaats decide to jump in, he could be a game changer in a Republican field where no clear front-runner has emerged.

"He would absolutely turn the whole race upside down and automatically be thought of as a top-tier candidate, if not the front-runner," the operative said. "His ability to mobilize an already active base would be vital. He would already have a massive statewide network."

Officially, however, Vander Plaats is still in wait-and-see mode.

"Bob has great respect for all those currently running, and is good friends with several of them," Dave Barnett, a spokesman for Vander Plaats said in a statement to ABC News on Wednesday. "He is giving it thoughtful consideration, and will make a decision on or before January 1."

Vander Plaats, who endorsed the GOP winners of the 2008 and 2012 Iowa caucuses, Mike Huckabee and Rick Santorum, is known as a political force in the state. But his previous attempts at running for office have all been thwarted. In 2002, 2006 and 2010 he tried and failed to run for governor of Iowa.

The five declared Republican candidates are Sam Clovis, a radio talk-show host from Sioux City; Joni Ernst, a state senator; Scott Schaben, a sales manager at an Ames car dealership; Matt Whitaker, a Des Moines lawyer and businessman; and David Young, the former chief of staff to Sen. Chuck Grassley.

They will share the stage Wednesday night at a debate held at Drake University that is sponsored by the group, Americans for Prosperity, and the National Review. All of the Republicans trail far behind Braley, the Democrat, in fundraising.

Last month, Vander Plaats used Sen. Ted Cruz's nearly 22-hour pre-shutdown speech on the Senate floor to hint at his growing interest in the Senate seat, tweeting on Sept. 24: " @TedCruz' bold leadership inspires me to consider run for US Senate. It'd be an honor to #standwithcruz and have 'we the people's' back."