Republican Chuck Grassley says he’s not concerned by a new poll that shows his bid for an eighth U.S. Senate term may be his toughest race since 1980.

A Des Moines Register/Mediacom Iowa Poll released this weekend shows nearly two-thirds of voters surveyed about Grassley’s race against Democrat Mike Franken have concerns about Grassley’s age. That includes more than a third of the Republicans who said they’ll vote for the 89 year old, despite their concerns about his age.

“If people think I can’t do the job, they ought to follow me around,” Grassley says. “I go to bed at 9. Get up at 4. (Run) two miles in morning. Get to the office before 6. Usually in the office until 6:30, quarter ’til 7. I have a full schedule when I’m in the office — you know committee meetings, caucuses, interviews like this that I do 52 times a year.”

Grassley made his comments this morning during an interview with Iowa radio reporters. Grassley has been emphasizing his more than four decades of experience in the Senate, but only a third of Iowa Poll respondents said they view Grassley’s tenure as an asset. If he’s elected, Grassley will be the longest serving senator. If Republicans win a majority of seats, he’ll be the president pro tempore of the Senate, which makes him fourth in line to the presidency.

“I don’t know whether people understand the seniority system but it’s a reality and you have to work within that system,” Grassley said. “Iowa’s going to be number one when I’m number one. Iowa’s always been number one for me. I love the people of Iowa. I love working for them.”

Grassley said if Iowans elect his opponent to the senate, Franken will have little seniority compared to the influence he’d have, perhaps as chairman of the Budget Committee in 2025 if Republicans have a majority in the senate.

Grassley’s seniority positions him to return as chairman of the Judiciary Committee for the next two years if he and his fellow Republicans win more seats than Democrats this November.