Passing a federal law banning almost all abortions after 20 weeks. Defunding parts of Obamacare. Weakening the Environmental Protection Agency. Kneecapping the Consumer Financial Protection Bureau, Elizabeth Warren’s baby, the new agency within the Fed to police consumer fraud. And—maybe, just maybe—letting a Supreme Court seat sit vacant until after the next presidential election.

That’s just the start of what happens if the Republicans win back the Senate this November. Imagine, posits a top aide to Mitch McConnell, a steady stream of legislation, much of it conservative, that will force Barack Obama to start vetoing bills for essentially the first time in his presidency.

And imagine a Republican Congress, with an eye toward 2016, that could take a number of steps to make life harder for presumed Democratic front-runner Hillary Clinton. First and foremost: continuing their investigations—indeed redoubling them—into the Benghazi tragedy.

Democrats have been feeling a wee bit better lately about this November. The Affordable Care Act is looking stronger. Southern incumbents like Mark Pryor and Mary Landrieu have seen some friendlier poll numbers.

But the fact remains that the GOP has a decent to good shot at taking the Senate this fall. A brand new Washington Post/ABC poll splashed a little cold water across Democratic faces. It finds Obama’s approval at an all-time low in Post polls. More ominously, Republican respondents said they were planning on voting in far greater numbers than did Democrats. So this is a reality Democrats and liberals, like it or not, have to think about.

In recent weeks, I talked with a broad range of Democratic senators and progressive insiders—and a few Republican and conservative ones—about this GOP future. Verdict: While most thought things would be worse, I was mildly surprised by the number who said that strangely enough, matters might actually improve a little. And I came away thinking that while Republicans in full control of Congress would obviously be well-positioned to tee things up for their presidential candidate, they’d more likely end up doing the opposite.

Yes, Things Can Get Worse

Let’s start with the bleak view. “If the Republicans win the Senate,” says Norman Ornstein of the American Enterprise Institute, “the conclusion they’re going to draw is ‘obstruction works,’ and they’re going to double down on it. So they’ll be thinking, ‘Why go out of our way to do stuff and why compromise when in two years we can win it all?’”

Ornstein’s frequent collaborator, Thomas Mann of the Brookings Institution, thinks that while it should make sense that Republicans eyeing a 2016 White House win would want to have some accomplishments to point to, we shouldn’t bet on it. “The interests of the party in ’16 are clear, but whether that proves sufficient to produce something positive out of the Republicans in Congress is a big reach,” says Mann. “They almost have an incentive to keep the economy going at a more tepid rate.”

Neera Tanden, president of the Center for American Progress, agrees. “A GOP Senate takeover would be terrible for Obama’s presidency,” Tanden says. “It would spell the end of any progress on any legislative action and with GOP control of both houses of Congress, Republicans would set up debates to help their presidential candidates in 2016. And of course, investigations of the administration would double.”

What about the senators themselves? New York’s Chuck Schumer predicts: “It would let loose six years of right-wing frustration. The potential for gridlock is enormous.”

Two of his more liberal colleagues, Elizabeth Warren and Sherrod Brown, emphasized the huge change in priorities we’d see if Republicans were in control of the Senate calendar. That, after all, is one of the main things a Senate majority can do—decide what does and does not get to the floor for consideration. With Mitch McConnell or any other Republican in charge of that calendar instead of Harry Reid, the Senate becomes an entirely different body.

“Their whole effort is grounded in their contempt for government,” Brown says. “On Medicare, on Social Security, on consumer protection, on regulation of Wall Street... If you want to know what a wholly Republican Congress would do, the thing to do is to look at what they’ve done in state capitals where they can. In Ohio, they’ve gone after voters’ rights, workers’ rights, women’s rights. They’d bring that to Washington.”

Warren notes another aspect of majority control that doesn’t get as much attention as floor votes but is also important: what kind of work the committees do and don’t do. Committee hearings rarely have the drama of, say, Henry Waxman hauling those tobacco executives up to the Hill a few years ago. But they matter. Groundwork is laid for future legislation, and that happens because the majority gets to determine what the hearings are about as well as the bulk of the witness list.

Warren had a fresh example at the ready on the day I spoke to her. “Right now, I just came out of a hearing on payday lending,” Warren told me. The payday lenders, who charge usurious loan rates to people living paycheck to paycheck, are one of Warren’s top targets—but they have a powerful lobby, and Republicans generally do their bidding. “If Republicans get in charge of the Senate,” says Warren, “a hearing like that has no chance of happening. They’ll get to roll over the issues of importance to the American people.”

The Pressure to Govern

But here’s the counterintuitive view, expressed by several folks: If Republicans have full control of Congress, they won’t have Harry Reid to kick around anymore. In a divided Congress, each party can point its finger at the other and say: “Obstructionist!” But if one party is running the show, the responsibility for getting results falls entirely on that party’s shoulders.

“If I were a Republican looking forward to 2016, I would actually want to get a little something done,” says William Galston of Brookings. “And if the president has any desire for his last six years to be anything other than trench warfare over the ACA [Affordable Care Act, as the Obamacare law is officially known], then maybe he’ll want to do something, too.”

Several people I spoke with noted that we do have precedent for this, and it’s hardly ancient history. “The model is the late ’90s template,” says Nicholas Eberstadt of the American Enterprise Institute. “Maybe a little less cordial.”

Or a lot less. But he has a point. In the 1994 election, the GOP took over the House and the Senate. At first, Republicans under Bob Dole and especially Newt Gingrich threw everything they could at Bill Clinton. But after a short while, Gingrich softened, and he and Clinton did pass some things—a landmark budget, and welfare reform.

“When Newt took over, at first, they were awful revolutionaries,” says Jim Kessler of Third Way, the centrist Democratic group. “They passed things that went nowhere. It was a Bataan Death March to a dead end. Then with the shutdown [in early 1996] they went too far, and then they realized that to keep their majority they had to govern.”

Hence, West Virginia Democrat Joe Manchin’s advice to the president: “My recommendation immediately would be for President Obama to sit down with Clinton and ask him how he did it. You don’t have to reinvent the wheel here.”

Having such a conversation couldn’t hurt. Bill Clinton is sitting on a library full of good political advice, and Obama should probably call him more often. But whether the Clinton-Gingrich model could be so easily transferred to Obama-Boehner—or, Lord help us, Obama-Cantor—is a wide open question. The parties are more dug in now than they were 15, 18 years ago, especially the Republicans. And they would probably think, as Norm Ornstein noted above, why should they play ball with 2016 coming? The best thing for them to do—in political terms, that is, albeit not for the country—is dig in, and drag down Obama’s poll numbers.

This would be the most effective way to harm Hillary Clinton, assuming she’s the Democratic choice in ’16. Says Bill Galston: “The most significant thing they can do to harm Hillary Clinton is to keep Obama’s approval numbers down. If you are running to succeed a two-term incumbent from your own party, you are in some sense running for his third term.”

There could be a few areas where agreement could be reached—for example, it might very well be in Republicans’ interest (with 2016 Latino voters in mind) to pass an immigration bill. On the other hand, they might not see it that way. They might see it as in their interest to try to paint Obama into a corner on immigration. And this raises the question of how the president would react to this new reality.

Can Obama Learn to Veto?

Here’s an undeniable truth that would flow from a fully Republican Congress. “Ironically,” says Don Stewart, a top aide to McConnell, “more legislation will actually pass, because we’ll just start passing things the House passed. Right now, Senator Reid’s main job is to be goaltender—to block President Obama from having to veto things.” To Stewart, Reid has prevented any number of bills that passed the House and could pass the Senate because “he wants the story to be ‘Republicans block.’ They’ve poison-pilled everything. We’ll take those out and pass things.” And then, what would Obama do?

This issue of the veto would surely be one of the main arenas of conflict if Republicans control both houses. Obama has vetoed less legislation than any president in modern history: just two bills, both in late 2010. George W. Bush vetoed 12 (and he had a cooperative Congress for six of his eight years); Clinton issued 37; George H.W. Bush, 44 (in four years!); and Ronald Reagan, 78. To find a president who’s vetoed fewer bills than Obama, you have to go back to 1881 and James Garfield, who logged zero vetoes, in no small part because just 200 days into his presidency, he was assassinated.

Obama hasn’t broken out his veto pen, says Robert Borosage of the liberal Campaign for America’s Future, because he hasn’t really wanted to be seen as confrontational. Let Reid and McConnell or Nancy Pelosi and John Boehner tear each others’ flesh; he’s wanted to float above that. With a wholly GOP Congress, says Borosage, that dynamic ends: “It dramatically forces the president to do something he’s never wanted to do, which is to define himself as a pole in the debate and be willing to stand up and veto things. That’s so against his character.”

But if this scenario comes to pass, he’ll have to veto. The Republicans will send him budgets and other bills with little—or big—poison pills. “With a Republican Senate, all kinds of things are going to reach his desk,” says Bill Samuel of the AFL-CIO. “There’ll be bills he needs to sign—funding the Defense Department, say—that they can add all kinds of malicious things to.”

To Grover Norquist, this is precisely the plan. Norquist doesn’t see major showdowns in the offing—just a series of minor ones that would nevertheless establish GOP priorities on the budget process, on the bet that the veto-shy Obama wouldn’t really change his stripes. “Lots of little things would slip in, and that’s the difference,” Norquist says. “Riders on appropriations. New EPA rules. Just make a list of everything he’s done by executive order and undo it by law in appropriations bills and make Obama sign or veto it.”

This circles us back to immigration. It seems far more likely that rather than pass a bill Obama could happily sign, Republicans would pass one he’d rather not sign—one without a path to citizenship, say—and box him in politically. “You could come up with an immigration reform that Obama would have a very hard time vetoing,” Norquist argues. “DREAMers, border security, STEM, and legal status. If you’re Obama, do you really want to say no to that?”

Frank Sharry, executive director of the pro-immigration reform America’s Voice, thinks that “the Republican dream of passing an immigration bill that puts Democrats in a pickle is a fantasy,” in large part because there are too many divisions within the GOP on the issue, divisions that will only be highlighted as their presidential contenders take center stage. Sharry might be right about that. But McConnell is nothing if not cagey. If he wins re-election and becomes majority leader, we can be sure he’ll think of plenty of ways to try to force Obama to accept GOP priorities, especially on budgetary matters, or issue a veto that would be difficult for some red-state Democrats to defend.

The GOP Policy Agenda: Look out ACA, CFPB, and Contraception

Political gamesmanship aside, there’s the question of what actual Republican policy priorities might be. Here’s where the liberal activists really get nervous.

Almost certainly, Republicans would pass bills with items similar to what’s been in the budgets written by Paul Ryan over the past few years: reducing Pell grants, food stamps, money for renewable energy. They’d target the EPA, as Norquist suggested, and they’d almost surely go after the Consumer Financial Protection Bureau, the new agency created by Dodd-Frank that reins in the bad practices of banks and other lenders. They’d try to change the oversight of the CFPB, giving business interests more control, or take it out from under the Federal Reserve Bank, where it’s now housed, which could reduce its authority.

This list could go on and on, but let’s look at just one issue area—contraception and reproductive rights. Right now, according to Donna Crane, the vice president for policy at NARAL-ProChoice America, the GOP House has passed or could quickly pass four bills that a Republican Senate would presumably endorse too:

*A law that would make it a federal crime for an adult to accompany a teen across state lines for an abortion and hold doctors liable for knowing that. “Think about that,” Crane says. “This would be the first time we’ve ever made a person carry their state with them, so to speak.”

*A law to ban abortion coverage in all state health-care insurance exchanges.

*A law to ban abortions after 20 weeks with an exception only for the life of the mother. This, Crane notes, has already passed the House.

*A law to end the contraception benefit in the ACA.

And speaking of Obamacare, what about that? It’s not clear Senate Republicans would even waste their time on repeal. That, they know Obama would veto in an instant. Don Stewart, of McConnell’s office, says they’ll go after specific items like doing away with the medical device tax, which appears to have 60 votes in the Senate right now.

AEI’s Nick Eberstadt muses: “The tactical opposition would be to starve the ACA by budgetary means. What happens if Congress doesn’t pass the health budget the president requests? That would be clarifying.”

It’s not clear just yet the extent to which that would be possible. The big-money portions of Obamacare—the Medicaid expansion, most notably—would have to be changed via legislation, which won’t happen as long as a Democrat is president. But smaller parts of the bill are subject to the appropriations process. “My gut sense is that the GOP won’t be able to truly destroy ACA,” says Harold Pollack, a health policy expert at the University of Chicago who had input into the law. “But they will have some success in cutting expenditures required to properly implement ACA and in generally making things nasty for the administration.”

And Finally, Looking Toward 2016

There’s more that I haven’t covered. Two big matters in particular: the filibuster, and presidential nominations. How would McConnell, if he’s majority leader, change the filibuster rules? Would he try to make it apply to fewer situations, so he could pass bills with 51 Republicans and just a few Democrats for cover? And what about nominations, especially judicial ones? Imagine, for example, that Ruth Bader Ginsburg were to retire in 2015. Would a GOP Senate even give her successor a hearing? And assuming it would, just how conservative a jurist would Obama have to nominate to get through a Senate that’s in Republican hands? I asked nearly everyone I interviewed this question, and while there wasn’t unanimity, there was a clear consensus that it wouldn’t be surprising to see the GOP give a nominee a hearing but sit on the vote, leaving the Supreme Court with only eight members until we see who wins the presidency.

And what of oversight and investigations? A Republican Senate could try to keep the Benghazi attack in the headlines until the day Hillary Clinton gives her acceptance speech, and beyond. This point underscores the extent to which 2016 hovers over everything discussed in this article. If the Republicans move into the Senate’s majority offices in the Capitol next January, they’ll be doing so at a time when the party’s 2016 nominee will start being more public in their intentions.

A Congress wholly controlled by the opposition party has plenty of ways it can help its presidential contenders. It can pass constructive legislation, it can pass “positioning” legislation that attempts to checkmate the other party; it also has the simple ability to help keep favorable issues in the news and unfavorable ones out.

But remember this: Legislators don’t take votes thinking about their presidential candidate’s career. They take votes thinking about their own careers, as Third Way’s Jim Kessler observes: “Congressional Republicans will do what they think is best for them to keep their majority in the House and the Senate. Legislative bodies are selfish, and they rarely sacrifice for others. They’d like a Republican president, but that’s a luxury.”

That’s exactly right. To return to Gingrich: He decided that passing welfare reform was in his caucus’ interest. Doing so took a big club out of Bob Dole’s hands. But that’s politics. Now, in the present day, passing immigration reform would probably help a GOP nominee. But legislators would have to decide: Would it help them? So far they haven’t thought so. Legislators will do what they think will help them. If it helps the nominee, great. If it doesn’t, too bad. And remember, many of these legislators represent deep-red districts and states, which probably don’t add up to more than 200 electoral votes—70 shy of what it takes to win.

And so, even if Republicans gain more power on the Hill, they may find that that power, and the imperative of keeping it, makes 2016 an even steeper climb than it already seems against Clinton. But that shouldn’t be much comfort for Democrats. A Republican Senate won’t be able to undo the president’s signature achievement, but it’ll take as many bites as it can out of what Obama has accomplished in the last six years. And trust me, those bite will hurt.