CHARLOTTE, N.C. — The heads of Democratic campaign arms charged with winning a majority in the House and keeping a majority in the Senate this evening made a largely economic case for Democratic control in Washington, D.C., and painted a sharp contrast with the GOP.

Rep. Steve Israel (N.Y.) and Sen. Patty Murray (Wash.) ticked through the accomplishments of a Democratic Congress and President Barack Obama, from health care reform to veterans benefits.

But both saved their most impassioned words for knocking the GOP.

“Simply, with a Republican Congress sitting shotgun,” Murray said. “Mitt Romney will put the middle class on the roof and take us for a long, painful ride.” The crowd cheered as the chairwoman of the Democratic Senatorial Campaign Committee alluded to an incident years ago during which Romney put his family’s dog on the roof of his car for a long road trip.

“Here’s their economic plan, ladies and gentlemen,” Israel said. “If you’re a millionaire, you win the lottery. If you’re a senior, you lose your Medicare guarantee.”

The phrase “middle class” was peppered throughout both speeches, honing a message that Democrats are looking out for and will look out for the wide swath of Americans who consider themselves in that economic strata — and that Republicans have not and will not.

Israel, the chairman of the Democratic Congressional Campaign Committee, took particular aim at GOP vice presidential nominee Paul Ryan, the House Budget chairman, and his Republican House colleagues’ votes.

Israel has made the changes to Medicare ensconced in Ryan’s controversial budgets a centerpiece of Democratic attacks on Republican candidates and Members. But Israel has a very steep uphill battle in taking back the House.

Murray, on the other hand, has at least an even chance of maintaining Democratic control of the Senate, even if by a razor-thin margin.

“Re-elect this president. Keep the Senate Democratic. And we can make sure every American family has the opportunities mine did,” Murray said. “Republicans may have given up on our country’s middle class, but President Obama never has; Senate Democrats never have and, together, we never will.”

The crowd cheered: “Pat-ty, Pat-ty, Pat-ty.”