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For most of this midterm election cycle, Democratic hopes have been pinned on retaking the House, while winning the Senate seemed a distant fantasy. The reason was quite simple: the House and Senate elections were being held in different countries, so to speak, with the lower chamber’s contests playing out nationwide while the upper chamber held its competition in a limited landscape of 33 states represented by 24 Democrats (ten of whom were in states carried by Donald Trump in 2016) and just 9 Republicans (only one of whom was in a state carried by Hillary Clinton). As a result, while a big national pro-Democratic swing would flip the House, it would take a lot more to flip the Senate, as David Wasserman pointed out earlier this year:

Fact: if all '18 election results were an 8% pro-Dem uniform swing vs. '16 prez results, Dems would gain 44 House seats & lose 4 Senate seats. — Dave Wasserman (@Redistrict) April 13, 2018

Beginning with Doug Jones’s improbable victory in an Alabama special election last December, however, there has been a narrow path to a Democratic Senate. Trump’s sagging popularity damaged his party’s Senate prospects in states that only marginally supported him in 2016, and a combination of poor GOP candidate recruitment and stronger-than-expected Democratic incumbency made a GOP sweep of the genuine pro-Trump states more and more problematic. Meanwhile, surprisingly strong Democratic challengers in unlikely states like Tennessee (Phil Bredesen) and Texas (Beto O’Rourke) boosted Donkey Party optimism even more.

As voting approaches, however, a Democratic House and a Republican Senate next year is again the most likely outcome. FiveThirtyEight’s sophisticated model based on polls, fundraising, political history, and historical trends gives Republicans a 7-in-9 (or 78 percent) chance of maintaining control of the Senate, while Democrats have a 3-in-4 chance (or 74 percent) of retaking the House.

Yes, probabilities are far from certainties, as Hillary Clinton could tell you. The Cook Political Report rates no fewer than nine Senate races as toss-ups (five are seats currently held by Democrats). If Democrats swept all the very close races as they did in 2012, they would definitely win the Senate. But if Republicans won all the toss-ups as they did in 2014, they could boost their majority by five seats. In the House, Cook shows 31 races as toss-ups, though they are much more unbalanced, with 29 being in districts currently held by Republicans. But some late breaks for Republicans could stem the Democratic tide.

If the current probabilities prevail, though, we’ll have Nancy Pelosi again holding the House gavel (barring some freshman revolt) for the first time since 2011, while Mitch McConnell would be Senate Majority Leader for a third consecutive Congress. Here are some of the implications:

(1) Divided government again: a House Democratic takeover would end a brief two-year Republican “trifecta” of control of the Executive and Legislative branches of the federal government. But divided government is hardly a novelty: it’s been the situation for 28 of the last 38 years. We will again see the Speaker of the House and the vice-president alternating like dueling puppets in standing and sitting during the president’s State of the Union address.

(2) No more partisan legislation utilizing the budget process. The Republican “trifecta” over the last two years enabled the GOP, in theory at least, to pass party-line legislation bypassing the Senate filibuster by using special budget “reconciliation” procedures on bills involving taxes and spending. It is how Republicans enacted their 2017 tax cut bill. But it failed them in the extended effort to repeal Obamacare because they could not keep their Senate caucus together. Divided government will take that weapon (which Paul Ryan once called “a bazooka in my pocket”) off the table entirely.

(3) Compromises to keep the federal government operating. Thanks to the Senate filibuster, regular appropriations bills already require significant compromises. But a Democratic House would mean Republicans no longer control access to the House floor or appointment of House as well as Senate members to conference committees to craft final bills.

(4) Divided control of congressional investigations. A Democratic House would most definitely deploy the investigatory powers of multiple committees to dig into and expose the rich, pungent soil of corruption and incompetence in the Trump administration. A Republican Senate will counter those efforts as much as possible, in a war for public attention that may become dizzying.

One important feature of the status quo would not change, however:

Republicans would maintain the Senate’s power to confirm Legislative and Judicial branch nominees. There would no longer be any need for the Senate to rush confirmations — including, were it to fail, the Supreme Court nomination now held by Brett Kavanaugh — through a lame-duck session between November 6 and Janaury 3, when the new Congress is sworn in. Since the House has no role in confirmations, Mitch McConnell would again be the ruler of that process. We will not, then, witness the sort of two-year gridlock over judicial nominations we might have witnessed if Democrats won the Senate.

In the long run, of course, no single Senate election is an end in itself, given the chamber’s rotating process in which a third of the body is up for reelection in every cycle. As Larry Sabato’s Crystal Ball recently pointed out, the results of this Senate election will affect the balance of power going into the next one in 2020:

Given that they are defending several red state Senate seats in 2018, Democrats would be very fortunate to win Senate control this November — and, in truth, just holding the line at 51-49 would be a victory, too. That could set Democrats up to win control in 2020, when Republicans are defending 22 of 34 seats being contested. That gives Republicans incentive to make the most of the opportunity they have this year to add to their majority — even an extra seat or two could give them the insulation they need to weather what 2020 could have in store.

So actually making net Senate gains this year could not only strengthen Mitch McConnell’s hand in the next Congress, but increase the odds that Republicans can prevent Democrats from pulling off their own trifecta in 2020. What happens on November 6, hypothetically, could help determine whether a newly elected President Warren or Harris or Gillibrand or Klobuchar or Winfrey — let’s limit the possibilities to just women at this point, as a gesture toward long-thwarted justice — will struggle to get her first Supreme Court nominee confirmed.