The election of Donald Trump has upended much of Gov. Larry Hogan’s reelection plan for 2018. Midterms are usually hard on the president’s party, which would have been great news for Larry Hogan except that Hillary Clinton didn’t win the election.

Midterm Elections Hard for Party with Unified Control
An examination of periods of unified party control of Congress and the Presidency since 1990 does not augur well for the Republicans. After Bill Clinton’s 1992 victory, Republicans swept in and took control of both the House and the Senate in 1994.

In the wake of 9/11, George W. Bush proved an exception, as the Republicans held up well in 2002. However, Democrats swept back into control in 2006, taking both the House and the Senate despite the structural barriers faced by Democrats in both cases.

Republicans also well remember that they eliminated the sizable Democratic majority in the House in 2010, just two years after Barack Obama gained election and ushered in unified Democratic control. While Republicans didn’t take the Senate, they made major gains, and the GOP took control of that body in the next set of midterms in 2014.

Democrats face enormous barriers to Senate gains in 2018 because they already hold so many of the seats up for election. However, the Republicans will likely face much less favorable trends than this year and this structural advantage won’t aid Larry Hogan.

Gubernatorial Elections Too
Indeed, a close examination of gubernatorial elections during midterms held under unified federal control by one party should not give Larry Hogan much comfort.

Republicans made stunning gains in 1994, as they picked up a walloping 10 governor’s mansions. They held the chief executive spot in 30 of the 50 states after this banner year election.

The post-9/11 2002 elections were less of an exception to the rule in gubernatorial than federal elections. The Republicans lost seats, though Bob Ehrlich did pick up the governor’s mansion in Maryland to become the first Republican since Spiro Agnew  in the 1960s to hold that office.

The 2006 midterms were a great year for the out party–the party that did not hold the presidency–as Democrats went from a minority of 22 state houses to 28 after the elections. Gov. Ehrlich lost reelection in Maryland.

As the out party in 2010, Republicans reversed that trend. They  went from having a minority of 23 governorships prior to the election to 29 afterwards. Yet Ehrlich, trying for a comeback, lost by an even greater margin to Gov. O’Malley. In 2014, despite already holding 29 governors, the GOP managed to pick up two more for a total of 31.

Declining Split-Ticket Voting
Something new happened in the U.S. Senate elections in 2016. Not one state elected a senator different from the party of the presidential candidate that won that state. This caps a long downward trend in the number of congressional districts that split their ticket.

Put another way, partisanship has grown much stronger and it is harder to win. Impressively, Hogan managed it with a strong prevailing wind behind him in 2014. But can he repeat the feat in 2016 when the Republicans appear likely to be facing a backlash based on historical trends? More discussion in Part III.