Sen. Charles E. Schumer (D-N.Y.) is interviewed at his office on June 3, 2015 in Washington, D.C. (Photo by Matt McClain/ The Washington Post)

After almost six months in the minority, Charles E. Schumer says Senate Democrats aren’t afraid to be obstructionists, detailing a strategy of blocking appropriations bills and other Republican agenda items until they get what they want.

Democrats are quickly learning that their only leverage point on Capitol Hill is through Senate unity, and in a wide-ranging interview, Schumer (D-N.Y.) said they are joining President Obama behind a plan to try to force Republicans to the negotiating table over everything from domestic and defense spending to highway funding and international tax reform.

Get ready for filibuster summer.

“There is pretty close to unanimity in our caucus that we are not going to just vote on individual appropriations bills until we have a plan as to how much overall money we’re going to spend and where that money is going to be allocated,” said Schumer, a member of party leadership.

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Schumer’s words reflect his reputation as a pugnacious partisan who takes on battles he thinks will resonate with voters. They may also foreshadow his style as the likely future Senate Democratic leader when Harry Reid (D-Nev.), the current holder of that title, retires at the end of this Congress. His advisers note, however, that in addition to his four years as a brutally successful campaign chief, he has also spent recent years working with Republicans on some key bipartisan measures including immigration and Senate rules.

The White House-backed plan to get Republicans to support more spending for domestic programs by blocking floor consideration of appropriations bills was developed in a series of closed-door meetings held over the course of several weeks.

Schumer, joined by Reid and Senate Minority Whip Richard J. Durbin, (D-Ill.), set out in recent days to rebound from weeks of party division over White House-backed trade legislation to sell the image of Democrats as a single, unbreakable force.

He said his colleagues are resolute and will not buckle when Republicans soon test their unity by bringing up for votes popular defense and veterans spending bills.

“We want to get a large agreement which the White House and the leadership of both parties in Congress buys off on,” Schumer said. “We’re not going to let them just cherry-pick and say we’ll give you a nice big number for defense and a nice big number for, say, veterans and energy and water and at the end of the day say, well, there’s not much left for HHS, take it or leave it.”

At issue is how to deal with the spending caps, known as the sequester, that were negotiated as part of the 2011 Budget Control Act and took effect in early 2013. Republicans have found a way to address their concerns about the impact of these funding restrictions on the military by tapping a war funding account for extra dollars, but Democrats are pressing for the caps to be boosted for domestic spending programs as well.

To maintain their leverage, Democrats have decided to block all spending bills starting with the defense appropriations measure headed to the floor next week. Durbin told reporters on Tuesday that there is also no ruling out a blockade of program authorizations, like upcoming votes on highway funding.

Democrats hope the plan will force Republicans to negotiate solutions to a series of expiring programs that Schumer calls “mini-cliffs,” recalling the the 2012 fiscal cliff breakdown where Democrats ultimately won $600 billion in tax increases on the wealthy.

The cliffs begin on June 30 when authorization for the Export-Import Bank is set to expire. By July 31, lawmakers will again be forced to fund a gap in the Highway Trust Fund before heading out of town for a month-long August recess. When they return, they will have one month before funding for the federal government runs out on Sept. 30, not long before the Treasury Department expects lawmakers will need to increase the debt limit.

The ball is already in Republicans’ court. The first test of the strategy came when Sen. Maria Cantwell (D-Wash.) agreed last month to support trade legislation that gives the White House extensive bargaining power in exchange for a promise from Senate Majority Leader Mitch McConnell (R-Ky.) of a vote on extending the Export-Import Bank’s charter.

Democrats said the deal, cut on the floor of the Senate amid a tense vote for the trade bill, ensures a vote on the bank and not in connection with a bill that the president has threatened to veto. But weeks later, they have seen little evidence that McConnell will follow through.

“You’d think that when there’s a promise that’s made out there and it was made on the floor, as I understand it, that they’d stick with it,” Schumer said. “The positive way to look at it is they intend to stick by their promise; they just haven’t figured out how.”

But blocking the appropriations bills outright goes one step further to undermine a vow from McConnell to once again fund the government through regular order. After weeks of battle over government spying programs and trade legislation, a breakdown on appropriations could end the narrative that Republicans have ushered in a new gridlock-free era of legislating in Congress.

The plan to block votes on spending bills also opens Democrats to charges of hypocrisy. They spent years deriding Republican delaying tactics as being obstructionist before now warming to the idea when it’s the best strategy for influencing the congressional agenda.

Republicans are still skeptical that this new brand of Democratic unity will hold when the funding bills are actually up for consideration.

“Senator Reid had previously said he was even going to block this defense authorization bill from coming to the floor,” Sen. John Barrasso (R-Wyo.) told reporters on Tuesday. “He said it was a waste of time, but it is on the floor now, and I expect that we’re going to be able to pass it with Democratic support as well.”

Beyond the immediate fight, Schumer said he is still working with Republicans on an international corporate tax reform proposal that he says could be the only policy area where bipartisan agreement remains.

“There might be a decent chance that there is something to be done on tax reform,” he said. “For Democrats, it would have to be linked to transportation.”

Schumer is the co-chairman of a bipartisan working group on tax reform with Sen. Rob Portman (R-Ohio). They have been working since January to craft a proposal they could sell in both the House and the Senate. Aides close to the process say the two are making significant progress.

Republicans would get a more business-friendly international tax code, and Democrats would be able to use money from transitioning to the new system to help pay for a large portion of the Highway Trust Fund.

But even that plan comes with serious caveats, making a deal a long shot at best.

“There are many on this side saying no infrastructure if we’re going to do corporate tax reform,” Schumer said. “And the president has said you won’t get corporate tax reform without infrastructure.”

All this plotting by Democratic leadership will be for naught if members feel the pressure to break ranks and support some spending bills and other must-pass legislation.

Schumer says he’s not worried

“We’re singing from the same page,” he said. “Democrats are unified.”