Average share of the vote received by the Democratic U.S. Senate candidate in a gubernatorial election cycle since 1990.

U.S. Rep. Beto O’Rourke (D-El Paso) has scheduled a “major announcement” for Friday that most observers believe will serve as his formal entry into the race against U.S. Sen. Ted Cruz (R). O’Rourke would also be running against three decades of history.

U.S. Rep. Beto O'Rourke

U.S. Rep. Beto O’Rourke

U.S. Sen. Ted Cruz

U.S. Sen. Ted

Democrats have lost 10 straight contests for the U.S. Senate since 1988, when former U.S. Sen. Lloyd Bentsen (D) won a fourth term over then-U.S. Rep. Beau Boulter (R-Amarillo), 59%-40%. A Democrat broken 40% in a gubernatorial election year just once since 1982, when Bentsen won his third term.

Recent Democratic senatorial nominees received 2% less of the vote, on average, when running in gubernatorial election cycles. That number jumps to 4.5% if one excludes the 2000 election. That year, Gov. George W. Bush first ran for president and Democratic voters nominated perennial candidate Gene Kelly for Senate. Kelly’s 32.3% is the all-time Democratic low-water mark for a Senate contest.

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