A Republican state lawmaker has jumped into Pennsylvania's 2018 U.S. Senate race.

Rep. Rick Saccone of Allegheny County held an official announcement conference in the Capitol Rotunda on Monday. He's the first to launch a challenge to Democratic Sen. Bob Casey, who has held the seat since 2006 and is seeking his third six-year term.

Saccone, who joined the House in 2011, is considered one of the chamber's more conservative members. Before that, he was a full-time international relations professor at St. Vincent College in Latrobe. He's also a former Air Force captain.

Saccone has long been a staunch Donald Trump supporter, and said he's extremely pleased with the president's first month in office.

"On basic policy itself, so far I've agreed with things that he's done," Saccone said.

And the Republican made it clear that he is going to come out swinging against Casey.

"The agenda that the people voted in last November represents, I believe, the people's hearts of Pennsylvania," Saccone said. "Bob Casey ... represents the opposite of that agenda. And he's up there undermining and subverting that agenda."

Saccone said he's pushing for "smaller government, lower taxes, fewer regulations, rebuilding our military, protecting the unborn, [and] supporting our Second Amendment," among other things.

Casey, he said several times, "is against all of those."

Saccone said entering the race early is a strategic move to raise his statewide profile.

So far, he's the only challenger in the field going up against the incumbent.

Casey is one of Pennsylvania's best-known politicians. His father — Bob Casey Sr. — served as governor from 1987 to 1995.