It's never too early to talk about 2020.  In addition to re-electing Donald Trump, Republicans are going to go all out to retake the House of Representatives.

The GOP will need at least 18 seats (19 depending on the outcome of the special election in N.C.-8), and Republicans hold a decided advantage in the partisan breakdown of competitive districts.  There are now 31 Democrats who occupy seats in districts won by Trump in 2016, while only three Republicans are in districts won by Hillary Clinton.  Many of those races won by Democrats in 2018 in Trump districts were extremely close.  In a presidential election year, where turnout will be considerably higher, Republicans feel they have a good chance to flip the House back to their control.

But history would suggest otherwise, according to the Cook political report:

But Democrats have history on their side: the House majority hasn't flipped twice in a row since 1954 and hasn't flipped during a presidential cycle since 1952. Democrats have gained House seats in five of the past six presidential elections (save for 2004, when Republicans drew a favorable new map in Texas) and in seven of the past eight presidential cycles, the net partisan seat shift in the House has been in the single digits.

Earlier in the decade, we theorized that for Democrats to win back the House, they would need either a resettlement program to move more of their voters into competitive districts or an unpopular GOP president in a midterm year.  In 2018, they got the latter.  Now, it's tough to see Republicans winning the House back unless President Trump's approval rating is significantly higher than today's 42 percent come 2020. 

In the age of Trump, I think it safe to say we can toss history out the window.  We are in uncharted partisan territory, and while voter attitudes are in flux, a key factor in determining House control in 2020 will be voters' opinion of the president.

And, of course, money:

However, financial deficits and retirements could complicate the GOP's path back.  In 2018, Democratic candidates outspent Republican candidates in 59 of the 75 most competitive races, in some cases by 2-to-1 or 3-to-1, according to data from OpenSecrets.org.  Democrats' dominance owed to their donor base's anger at Trump and their ability to bundle and direct small-dollar contributions efficiently through ActBlue.

Republicans argue 2020 will be different because Democratic House candidates will be competing against presidential contenders for attention and cash.  But Democratic incumbents could continue to benefit from an increasingly wealthy base that's angry at the president.  And, GOP candidates could find it more difficult to raise money out of power.

Republicans need to avoid a repeat of 2008, the last time they were newly in the minority and morale foundered.  That cycle, 26 Republican incumbents headed for the exits and Democrats picked up nearly half of their seats.  In fall 2008, the DCCC outspent the cash-strapped NRCC by a whopping $75 million to $21 million and had the airwaves to themselves in dozens of districts, ultimately helping Democrats gain 21 seats.

In 2018 there were 50 GOP incumbents who retired or were defeated in primaries.  A lot of them refused to run, because they knew their races were uphill battles.  The Republicans have sloughed off most of their vulnerable members and stand now to take advantage of a more favorable map.

But much depends on the president's legal troubles and how those problems will affect his popularity.  The Republican party is Trump's party, and it will stand or fall based on the president's standing with the voters and whether he can convince them to oppose the radical socialist agenda Democrats will be pushing in 2020.