The 12-state region will see its collective delegation decrease in size for the 10th consecutive decade, although at its lowest rate in a half-century.
Only three presidential candidates have attempted a third major party bid after two failed attempts in the modern primary era.
Only five of 55 U.S. Senate partisan winning streaks of eight in a row have been halted in the subsequent contest during direct election era.
Mandel vs. Brown will be just the second U.S. Senate rematch in Ohio history; Mandel seeks to become the fifth failed nominee to come back and win a seat.
Only one of the 73 Republican U.S. House members from Trump states with Democratic US Senators on the 2018 ballot has mounted a challenge.
The 10 Trump states with Democratic incumbents have voted for senate nominees from the opposing party of the sitting president 62 percent of the time over the last 50 years.
Only one sitting or ex-secretary of state has won the governorship in Ohio history.
Heller is the only Republican among the 15 U.S. Senators who serve states in which their party holds a minority of U.S. House seats; a dozen (including Heller) are up for reelection in 2018.
Republicans would break a party record if eight U.S. Senate nominees are elected from states voting Democratic for president.
The first term U.S. Senator is enjoying a comfortable lead in the polls, but modern political history suggests he should be doing even better.