DES MOINES, Iowa (AP) — Iowa Sen. Chuck Grassley says his age won't slow him down as he runs for a 7th term.

"I think that age isn't a factor or I wouldn't be running for office — or I wouldn't be running this morning," said the spry 81-year-old Friday, referring to his regular jogging sessions.

The six-term Republican held the first fundraiser for his 2016 campaign earlier this week and is nearly halfway through his annual tour of all 99 Iowa counties. Grassley, the second oldest member of the Senate, has been in elected office since 1959 and is hugely popular in his home state, where he is known for his vigorous work ethic and down-home charm.

A February poll from Quinnipiac University showed that 67 percent of voters approve of the job Grassley is doing and 55 percent say he should get another term. That poll of 1,089 Iowa voters had a margin of error of plus or minus three percentage points.

So far he does not have a major Democratic challenger even though Iowa is a political swing state that twice supported Democratic President Barack Obama. Former state lawmaker Bob Krause is planning a bid and other Democrats are considering the race.

"I think that challenging Chuck Grassley is an uphill battle, but Iowans are frustrated with Washington, just as they are in the rest of the country," said Norm Sterzenbach, former executive director of the Iowa Democratic Party.

Grassley currently serves as a chairman of the Senate Judiciary Committee, where he has focused on government oversight and sought legislation to protect whistleblowers. He also serves on the Finance, Budget and Agriculture committees, as well as the Joint Committee on Taxation. Another top priority has been promoting wind energy and renewable energy sources.

During a taping of the public affairs program "Iowa Press" Friday, Grassley said he should be re-elected for his government oversight efforts.

Justin Barasky, spokesman for the Democratic Senatorial Campaign Committee, argued that Grassley was "out of step" with many Iowans. Among his examples was Grassley's signing of an open letter to the leaders of Iran last month aimed at undercutting Obama administration attempts to reach a nuclear deal with that country.

If elected to another term, Grassley would be 83 at the start and 89 at the finish. He was first elected to the Senate in 1980, after a stint in the House of Representatives and time serving in the Iowa Legislature. Grassley is currently serving with Republican Sen. Joni Ernst, who was elected last year to replace retiring Democrat Tom Harkin.