Sen. Jon Kyl, R-Ariz., was sworn in as the newest member of the U.S. Senate on Wednesday after he was picked to replace the late Sen. John McCain for at least the remainder of the year.

Kyl returns to the Senate after leaving in 2012 following an 18-year tenure in the upper chamber. His appointment gives Republicans 51 voting members again for the first time since December, when McCain left Washington for cancer treatment.

Senate Majority Leader Mitch McConnell, R-Ky., sung the praises of Kyl, who served as the No. 2 Senate Republican until his 2012 retirement. McConnell called him one of the "most effective legislators" he ever served with.

"Today, the great state of Arizona has sent us his successor, who's as well equipped as you can imagine to do just that," he said. "Our friend and former colleague, Sen. Jon Kyl, R-Ariz., is one of the most serious, most expert, most effective legislators with whom I've had the pleasure of serving."

"He built a reputation as a steady and energetic public servant who put his state and his country first," McConnell added. "On a point of personal privilege, I'm really glad that we'll have Jon back with us. He has great judgment, an even keel, he's a team player, a true friend and inspiring example of what a senator can and should be."

McConnell added that he is glad Kyl is back for the remainder of the year as the Senate has a lot to tackle in that time, including finalizing appropriations for the year and confirming Judge Brett Kavanaugh to the Supreme Court.

Kyl's presence is of particular importance as it gives Republicans an extra vote in their hopes of confirming Kavanaugh, whom Kyl has helped guide through the confirmation process since Trump announced his nomination in July.

With Kyl's return, Republicans could now lose one GOP senator and still have Vice President Mike Pence break the resulting 50-50 tie.