The comments closely mirror remarks from Democratic Congressional Campaign Committee chief Steve Israel (D-N.Y.), who said Thursday that Ryan is a "down-ballot disaster for Republicans across the country."
Pelosi spoke on the issue during her weekly press conference.
"This is a value on the ballot, not an issue," she said of Medicare.
Ryan, who serves as House Budget Committee chairman, has proposed to partially privatize the entitlement, allowing seniors to enroll in the traditional program or take a subsidy to buy private insurance.
Republicans argue that the reform is necessary to ensure Medicare's solvency and survival for future generations. Democrats say, as Pelosi did Thursday, that Ryan's plan would "sever the Medicare guarantee" for seniors by making them contribute more toward their healthcare.