As speculation swirls about who might seek his job, Sen. Tom Harkin is trudging ahead on a promise he made when he announced his retirement — pushing ahead with far-reaching legislation aimed at curing some of the bedrock problems in the American middle class.

Harkin, D-Iowa, says he will reintroduce a measure requiring paid sick leave. And this week, he’ll renew his push for a pension-like plan aimed at boosting what he believes is the dangerously low amount of money Americans have set aside for their older years.

Harkin, who is 73, announced two weeks ago that he wouldn’t run again in 2014. The news shocked Iowa’s political sphere and, since then, all but one in the state’s delegation in the U.S. House has begun mulling whether they’ll seek his job.

Rep. Bruce Braley, D-Iowa, was the first to step forward with an announcement Thursday that he has formed a campaign committee. Meanwhile, Reps. Tom Latham and Steve King, Republicans, are considering it, too.

As for Harkin, he’s been embroiled in a controversy over the institute named after him at Iowa State University. Last week, the senator withdrew his offer to turn his congressional papers over to the institute, saying he had doubts about its ability to conduct unfettered research at Iowa State. College officials have rejected the idea that it would put limits on the think tank.

On his weekly conference call, Harkin took a raft of questions on both topics. Little noticed was his announcement that he would be introducing a bill to give workers the chance to earn seven paid sick days a year.

The bill is one of a package of proposals the senator will push this year from his perch as chairman of the powerful Health, Education, Labor and Pensions Committee, known as HELP. “We still have an unfinished agenda when it comes to helping working families,” Harkin said.

On Tuesday, Harkin will make what his office says is a major policy speech at the Center for American Progress, promoting his Universal Secure and Adaptable Retirement Fund proposal. The plan is aimed at improving Americans’ retirement security.

Harkin has argued the country faces a “retirement crisis ... simply too big to ignore.”

His proposal would have workers pay pre-tax dollars into their own retirement fund, and when they retire, they’d get regular payments. The plan combines the reliability of a traditional pension with the portability of a 401(k) plan, Harkin’s office says.

Employers who don’t offer work-place retirement plans with a minimum contribution amount would have to offer this to their workers and make a contribution themselves. Employees could opt out of the plan.

“This is all part of his HELP agenda for the next two years,” Kate Cyrul, a spokeswoman said Friday. She said Harkin also will be pursuing proposals to increase access to early education, lower the costs of higher education, improve employment opportunities for people with disabilities and implement the health-care law.

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Some business groups have raised reservations about the retirement plan. At a HELP Committee hearing last year, an executive at the U.S. Chamber of Commerce praised the country’s current private retirement system, saying participation is growing. In an interview, Aliya Wong, the chamber’s executive director of retirement policy, said the Harkin plan would have a “pretty substantial” impact on businesses because of the required contribution.

“There is a gap in retirement savings. We would disagree this is the right way to go about resolving it,” she said, noting the chamber anticipates working with the committee on retirement issues. Certain funding rules for multi-employer pension plans expire in 2014, providing an avenue for changes.

Harkin has also said he’ll seek changes in Social Security to increase benefits, and that he expects another vote on the United Nations treaty on the rights of people with disabilities. The treaty failed when it first came before the Senate earlier this year.

Many of the proposed changes, such as the new kind of pension plan and paid sick leave, will undoubtedly face significant hurdles, especially in the Republican-controlled House of Representatives. These kinds of proposals also aren’t likely to be top of mind for congressional leaders or the White House as they face issues such as immigration, gun control and the debt.

Still, Harkin shows no less appetite for battle for those things he says have driven his career, even if those battles will no longer be fought at the ballot box.

“This is not a goodbye speech,” Harkin told the state Democratic Party’s central committee two weeks ago, according to a Radio Iowa recording of the speech. “I’m going to be very much a part of you for the next two years and beyond. Even after I leave the Senate, I don’t intend to get lost some place. I’m very much involved in the policies of our country, meeting that moral test of government that I spoke about when I first started.”