Republicans angry at President Barack Obama’s muscular use of executive authority are returning from recess more focused on litigation than on legislation.  

The Supreme Court’s docket for this term is unusual for including two cases with potential to reorder the balance of power between the legislative and executive branches. In oral arguments six weeks ago, the justices seemed open to a significant clipping of the president’s appointment power when the Senate is in recess. On Monday, the court will consider how much an administration can do through regulation before it has seized the congressional prerogative to alter the law.  

Both decisions, expected by June, could change the relationship between Congress and the White House in ways that constitutional lawyers and politicians will be arguing about for decades. In the shorter term, though, the outcomes may play a meaningful role in the midterm campaigns and then in Obama’s final two years.  

If Obama loses one or both cases, even on narrow grounds, Republicans can be counted on to crow that their complaints about an “imperial presidency” have been vindicated. They likely would further say that, to make sure his power stays diminished, they need to be rewarded with more seats in the 114th Congress. If Obama’s positions prevail, the GOP will seek to raise more money, and court more base voters, with a slightly different argument: that electing an all-Republican Congress is the best way to prevent this president from even more executive overreach. The recess appointment fight began in January 2012 when Obama put three people on the National Labor Relations Board who would normally require confirmation, contending that the pro forma sessions at the time were a sham that couldn’t mask the reality that senators were on a long holiday break. Senate Republicans, and the losers in a subsequent NLRB decision, cried foul, contending that at a minimum the Senate gets to say when it’s in recess. The lower court ruling now before the Supreme Court went further, calling decades of practice into question by declaring that recess appointments were only valid between the annual sessions of Congress and could only involve positions that came open in that narrow window.  

Until recently, the regulatory power case has been viewed mainly as an environmental story. The Supreme Court could slow government efforts to combat global warming, because the dispute is about how much authority the EPA has in limiting greenhouse gas emissions from power plants and other big industrial complexes.  

The case has become part of the balance of power narrative during the past month, since Obama promised in his State of the Union address to do whatever he could to advance his agenda “with or without Congress.”  

His vow inflamed Republicans , already angry about Obama’s robust exercising of power on a wide range of issues. They don’t like that he slowed the health care law’s implementation, eased up on deportations, relaxed welfare work requirements, declined to defend the Defense of Marriage Act in court and acquiesced in the Colorado and Washington marijuana legalization laws.  

More than 100 Republicans have joined an effort to compel the House to go to court in an effort to rein him in, but that strategy has a slim chance of success because judges generally shy away from entering disputes they view as overtly political. The reality that suing is a long shot has heightened Republican rooting interest in the EPA case. Two dozen members have signed legal briefs urging the justices to rule against the Obama administration.  

One was filed by Senate Minority Leader Mitch McConnell and the other six members of his party in the coal-centric Kentucky delegation. A second was submitted by five conservative senators from the Midwest. The Southeast Legal Foundation, a small-government think tank, filed a brief that was joined by 12 House members, including all three running for Georgia’s open Senate seat and a trio of senior Energy and Commerce members.  

The Supreme Court in 2007 ruled that the EPA had authority under the Clean Air Act to regulate greenhouse gas emissions from new cars and trucks after formally establishing that carbon dioxide poses a danger to public health. With that ruling in hand, the agency in 2010 started creating a permitting system for stationary sources of carbon pollution. The EPA’s power to do that is not at issue in the new case. Instead the question is whether the agency has leeway to tailor a provision of law written in 1970 to fit current circumstances.  

The Clean Air Act generally requires the EPA to regulate sources of 250 tons annually of a known pollutant. Applied to greenhouse gases — which are far more ubiquitous than, say, lead — that would mean federal permitting for renovating or building schools, shopping complexes, hospitals and apartment towers.  

To avoid what it terms those “absurd results,” the EPA wants to regulate only industrial complexes that generate at least 75,000 tons of carbon pollution a year — the several hundred facilities that account for about a third of all American greenhouse gas emissions.  

The Obama administration says the law is flexible enough to permit such a move. Republicans couldn’t disagree more.  

While agencies are generally allowed to set “rules that implement the will of Congress” and “may do so by filling in the details of general legislative commands and clarifying ambiguous statutory provisions,” the McConnell brief argued, “neither the EPA nor any other entity in the executive branch may override the will of Congress by amending or disregarding specific, unambiguous statutory text.”  

The brief signed by the 12 House Republicans sounds an even shriller alarm — one that makes the stakes in the recess appointment case seem small by comparison. The EPA’s regulations, they assert, are “an intolerable invasion of Congress’s domain that threatens to obliterate the line dividing executive from legislative power.”