The head of the House Democrats' campaign arm said Wednesday that the recently unveiled House Republican budget will be the central issue during the remainder of the 2014 midterm campaign.

"This will be the defining issue in the midterm elections," Democratic Congressional Campaign Committee Chairman Steve Israel (D-N.Y.) told reporters in an appearance at the National Press Club. He argued the budget is harmful to the middle class, and "tightens the noose" around them.

Israel announced the launch of a new DCCC initiative called "Battleground Middle Class." The effort will "hold Republicans accountable in their district," Israel said. It involves robocalls in 76 districts, online advertisements, and an early field effort investment.

House Budget Committee Chairman Paul Ryan (R-Wis.) rolled out the GOP budget on Tuesday. It would slash more than $5 trillion in federal spending over the next decade, mainly via repeal of the federal health-care law. It would also remake Medicare as a voucher-like system, something Democrats have heavily targeted in previous elections.

The budget stands no chance of winning passage in the Democratic-controlled Senate.

House Democrats face a steep uphill climb in their quest to win the majority. They need to pick up 17 seats -- a goal that even Democratic strategists privately acknowledge is highly unlikely against the backdrop of President Obama's lingering unpopularity.

"It's a tough climate for us right now," said Israel, adding, " But, I believe this Republican budget helps change the narrative by reminding voters who has their backs."

Israel said he sees about 52 districts in play right now. Democrats, he said, will continue to go on offense against Republicans advocating a repeal of Obamacare, despite the party's recent loss in Florida's 13th district special election. Republican David Jolly won that race, who supported repealing the law.

"We are doing a very thorough diagnostic and clinical analysis" of the outcome in Florida, Israel said.

Israel said the the tea party "has lost its luster." Earlier this cycle, House Democrats sought to use the tea party as a foil in the lead-up to the elections.

Republicans responded to Israel's remarks about the GOP budget by arguing that the health-care law and Obama's image will be the focal points for the rest of the campaign.

“In 2012-- with President Obama on the ballot -- Steve Israel called Paul Ryan the Democrats’ ‘majority maker,’ yet his party didn’t even come close. We hope Democrats keep running on their support of ObamaCare’s drastic cuts to Medicare, opposition to a balanced budget, and support for an unpopular President," responded National Republican Congressional Committee spokeswoman Andrea Bozek.