Marco RubioMarco Antonio RubioRubio in Colombia to push for delivery of humanitarian aid to Venezuela On unilateral executive action, Mitch McConnell was right — in 2014 On The Money: Trump declares emergency at border | Braces for legal fight | Move divides GOP | Trump signs border deal to avoid shutdown | Winners, losers from spending fight | US, China trade talks to resume next week MORE on Tuesday officially won the endorsement of Rep. Trey GowdyHarold (Trey) Watson GowdyTrey Gowdy joins Fox News as a contributor Congress must take the next steps on federal criminal justice reforms Lynch testimony marks final interview of GOP-led probe MORE, the chairman of the Select Committee on Benghazi, as the two hit the stump together in Iowa.

“It’s not my job to tell you who to vote for, but I’m going to tell you who I’m going to vote for,” the South Carolina congressman said while introducing Rubio at a town hall event.

“I’m going to vote for Marco Rubio, and I'll tell you why. National security and public safety are the most important issues to me and there is nobody better on those two issues than Marco Rubio.”

He immediately chided President Obama, who has filled out his NCAA basketball bracket on ESPN each year of his presidency.

"Our Founding Fathers did not give us a commander-in-chief to fill out March Madness basketball brackets, or to sample every golf coast on the Eastern seaboard," Gowdy said.

"The most precious things in my life are my wife and two children, and I trust Marco Rubio to lead a country safely that has [the] most precious things in my life in it."

Gowdy's support could be crucial in South Carolina — the third nominating state — and could bolster Rubio’s credentials with the party's base, even as rival Sen. Ted CruzRafael (Ted) Edward CruzEl Chapo's lawyer fires back at Cruz: 'Ludicrous' to suggest drug lord will pay for wall Democrats have a chance of beating Trump with Julian Castro on the 2020 ticket Poll shows competitive matchup if O’Rourke ran for Senate again MORE (R-Texas) takes shots at his conservative credentials.

Gowdy noted his role as the chairman of a House Judiciary subcommittee on immigration as he lauded Rubio's commitment to border security in light of the recent spat with Cruz.

"If I were not convinced that Marco Rubio was the person to ensure border security, interior security, and employment security, I wouldn't be wasting your time," he said.

And Gowdy joked that he knew Rubio is a true fiscal conservative after he gave him a campaign tie for Christmas.

“The wrapping paper cost more than the tie,” Gowdy joked.

Over the weekend, TownHall.com first reported that Gowdy would endorse Rubio as he hit a three-day swing in Iowa with the White House hopeful, but Tuesday marked the official confirmation of that report. The announcement was supposed to come during an event Monday, but the campaign cancelled it due to severe weather in Iowa.

Gowdy has earned praise from conservatives for his work on the committee, but drawn the ire of Democrats who believe the panel is targeting Democratic frontrunner Hillary ClintonHillary Diane Rodham ClintonRoger Stone shares, quickly deletes Instagram photo of federal judge on his case Barack, Michelle Obama expected to refrain from endorsing in 2020 Dem primary: report Why the national emergency? A second term may be Trump’s only shield from an indictment MORE ahead of 2016. A Rubio staffer introducing Gowdy noted that his investigation is "exposing the incompetency of not only the Obama administration, but Sec. of State Hillary Clinton."

Soon after the town hall ended, Gowdy hit Rubio's supporters with an email soliciting donations.

This story was updated at 3:28 p.m.