Republican Sen. Chuck Grassley of Iowa won an 8th term to the Senate Tuesday, making him the most senior member of the upper house.

Grassley beat Democrat Mike Franken, a former Navy admiral. He garnered 56.1% of the vote to Franken's 43.9%, his closest election since he unseated Democratic Sen. John Culver in 1981.

Before entering the U.S. Senate Grassley was a congressman for Iowa's third district and a state representative. He is expected to serve as the Senate's president pro tem if Republicans win the Senate, making him third in line of succession for the presidency behind the vice president and House speaker.

The senator, 89, will be 95 if he completes his six-year term, making him the second-oldest member of Congress in history. U.S. Sen. Strom Thurmond served until he was 100.

"If I'm re-elected to the United States Senate, I will be No. 1 in the United States Senate," Grassley said at an Oct. 6 debate. "Iowa will be No. 1 on my agenda whether you're Republican, Democrat or independent. And my opponent will be No. 100."

Franken won in five Democratic-leaning counties including Johnson County, home of the University of Iowa, and Polk County where the state Capitol is located. Grassley claimed victory in the remaining 94 counties, including Scott County which voted Democrat in 2020.

Franken noted Grassley's long tenure in the Senate during his campaign. Many voters were concerned that the candidate's age may be an issue.

According to a June Des Moines Register/Mediacom poll, 60% of likely voters said Grassley's age was a concern rather than an asset.

"I hope that just how I conduct myself daily ought to convince people that I not only have the ability, but I will do it," Grassley said in October. "And, unless God intervenes, I'm going to be in the Senate six years."