Here’s why the 2018 Senate election will be crucial for President Trump and his Democratic foes

In the partisan battle zone that is Washington, there is one conquest that could turn the fight decisively in Republicans’ favor: winning 60 seats in the U.S. Senate.

With control of the House, a filibuster-proof Senate majority could empower President Trump and his congressional allies to push through legislation and approve high-level appointees, such as Supreme Court nominees, with Democrats in the minority powerless to stop them.

That is why the 2018 midterm election is shaping up as crucial for Trump and congressional Republicans, as well as Democrats fighting to protect President Obama’s legacy and hold the line on further GOP advances.

After Democrats netted two seats in the Senate last year, Republicans hold a 52-48 majority, meaning the GOP would need a gain of eight seats to reach a filibuster-proof margin.

(That assumes party lawmakers stick together and vote as a bloc, which is never a certainty, as demonstrated by the withdrawal Wednesday of Trump’s nominee to head the Labor Department, Andrew Puzder, in the face of Republican opposition.)

So what are the odds?

After bruising confirmation battle, EPA nominee Scott Pruitt expected to clear Senate vote ?

If the 2016 election proved anything, it is the foolhardiness of making political predictions, especially this far out. That said, Republicans start in a strong position — though an eight-seat gain still seems like a considerable reach.

The Democrats regaining control of the Senate, which they lost in 2014, is almost impossible to fathom.

When is the midterm election?

Nov. 6, 2018.

How many Senate seats will be contested?

Thirty-four, or just more than a third of the Senate.

Why are Republicans strongly positioned starting out?

Because Democrats will have to defend 25 seats to just nine for the GOP.

Gee willikers! Why are those numbers so lopsided?

Senate terms last six years; the seats that are coming up in 2018 are ones that were last on the ballot in 2012, when Obama was seeking reelection and Democrats, riding his coattails, gained two seats. That simply means more Democratic-held seats will be contested in 2018.

The reverse took place in 2016. After making significant gains in the tea party election of 2010, Republicans had to defend 24 Senate seats compared to Democrats’ 10.

Any other reason Republicans are strongly positioned heading into 2018?

Indeed. Ten of the 25 seats that Democrats are defending are in states that Trump carried — in some instances by huge margins. He won West Virginia, where Joe Manchin is seeking reelection, by 42 percentage points, and North Dakota, where Heidi Heitkamp is seeking a second term, by 36 percentage points. He also carried Montana, Indiana and Missouri — where Democratic incumbents are facing reelection — by double-digits.

What do historical trends suggest?

Many of those didn’t hold up so well in 2016, when Trump pulled off one of the biggest political upsets of modern times. So it may be best not to go there.

Ah, c’mon!

OK, fine. Historically, the party holding the White House loses congressional seats in the first set of midterm elections after a president takes office. That offers Democrats hope. But the pattern is repeated more often in House races than Senate elections.

According to the nonpartisan Cook Political Report, the party in power lost House seats in nine of the last 10 elections held at the midpoint of a president’s first term, but gave up Senate seats in only six of those 10 elections. (In a rarity, the GOP actually gained House and Senate seats in 2002, even as Republican George W. Bush sat in the White House, owing to a surge of support following the Sept. 11, 2001, terrorist attacks.)

Would an eight-seat pickup be a lot? A little?

Gaining eight seats would be on the upper end of achievement, based on election results going back the last 60 years. Republicans picked up nine Senate seats in 2014, but that was in Obama’s second midterm election, a time of particular political weakness. It would be pretty remarkable for the GOP to post that sort of gain with a member of their own party sitting in the White House.

Why is that?

Because supporters of the “out” party, that is the one not in control of the White House, tend to be more motivated to turn out than supporters of the “in” party. Part of that may be because, by nature, people are more likely to act — in this case vote — out of anger or dissatisfaction than contentment.

Typically in non-presidential elections, there is a significant falloff in turnout among voters who lean Democratic, in particular minorities and young people. That was certainly the case when Obama was in office.

Right you are. So what’s the question?

Aren’t many of those same groups now highly animated and involved in protests directed at Trump?

Very much so. The big question is whether they’ll still be be animated enough to vote in large numbers in November 2018. If so, that would make the Republican reach for 60 seats even tougher.

Say, didn’t President Obama once have a 60-seat Democratic majority? Why wasn’t he able to get more done?

Democrats did hit the magic 60-seat mark early in Obama’s first term. (Or, to be precise, Democrats held 58 seats and were joined by two independents who voted with the party.) But a delay in seating Minnesota’s Al Franken — due to an election recount — the absence of an ailing Robert Byrd of West Virginia and the death of Massachusetts’ Edward M. Kennedy meant Democrats enjoyed that 60-seat high mark for only a relatively brief time.

They lost their filibuster-proof majority in February 2010 upon the swearing-in of Republican Scott Brown, who won a special election to finish Kennedy’s term.

What are the prospects of Democrats winning back control of the Senate?

That would require a net gain of three seats, which seems very, very, very unlikely given the high number they must defend and Republicans’ comparatively small exposure. But the election of Trump proved that just because something is unlikely — even very, very, very unlikely — does not mean it can’t or won’t happen.

mark.barabak@latimes.com

Twitter: @markzbarabak

ALSO:

Flynn’s ouster deepens questions about Trump’s relations with Russia

Trump’s vow to scrap the Paris climate change accord faces skepticism from corporations, GOP moderates

There’s a long history of presidential untruths. Here’s why Donald Trump is ‘in a class by himself’