Democrats say presumptive GOP vice presidential nominee Rep. Paul Ryan is a senior citizen’s worst nightmare, but retirees seem to have no problem writing him checks.

One of the most prolific fundraisers in Congress, Ryan has drawn nearly $400,000 from retirees this election cycle, dramatically outperforming most House lawmakers, according to data collected by the Center for Responsive Politics.

The seven-term Wisconsin Congressman and House Budget chairman has come under fire for the controversial budget proposal he released last year that called for dramatically reshaping Medicare and repealing President Barack Obama’s health care law. The plan would transition Medicare into a voucher-like system by 2022 and strike the 2010 health care law – two ideas that Democrats say would be devastating for older Americans.

Just about 13 percent of residents of Ryan’s district, which blends the wealthy Milwaukee suburbs with some of the state’s largest industrial areas, are 65 years or older, ranking 203rd out of the 437 districts, including Washington, D.C., and Puerto Rico, according to 2010 census data.

By comparison, Rep. Vern Buchanan (R-Fla.), who represents more people over age 65 than any another Member of Congress, according to 2010 census figures, has raised just $113,000 from retirees so far this cycle.

Rep. Roscoe Bartlett, a 10-term Republican from Maryland, where about 13 percent of residents are 65 and older, brought in $25,000. And Rep. Jim Sensenbrenner, whose neighboring Wisconsin district is 15 percent 65-plus, brought in only $7,000 from retirees.

But older Americans haven’t always made it rain for Ryan. In the 2008 cycle, he raised just more than $94,000 from people who self-identified as retired. That changed in the next cycle, after he released the first version of his budget plan and its Medicare overhaul, when he raised more than $340,000 from retirees.

So, should Democrats rethink their talking points? Not so fast, says Bob Biersack, senior fellow at the CRP and 30-year Federal Election Commission veteran.

“These are rich retired people who have the money to contribute to candidates, so they may think differently than other retired people,” Biersack said. “Medicare stability may be less salient for them.”

Lawmakers of Ryan’s stature often draw from donors beyond their districts, and older Americans tend to make up the bulk of individual donors. Since Ryan relies heavily on individual contributions to begin with, it is not entirely surprising that retirees sustain Ryan’s campaign coffers.

Donors are required to provide their occupation when contributing to federal candidates. Retired individuals have given more than $13 million to federal candidates this cycle, including Obama and presumptive GOP presidential nominee Mitt Romney, according to the center.

Though Ryan’s haul from retirees is still a small fraction of the $4.3 million his campaign has raised – all of which can now be turned over to the Republican National Committee to advance the Romney/Ryan ticket – it is almost as much as he has raised from donors employed in the securities, insurance and health professional industries combined.