History argues for Democratic Senate gains

History argues for Democratic Senate gains
© Greg Nash

Senate Democrats have one enormous advantage even as they face one of the most difficult political terrains in recent memory: They are not the party that controls the White House.

A new analysis of election results over the past 10 midterm cycles underlines that since 1978, incumbents of the party out of power, even in states the president carried in the previous election, are overwhelmingly likely to win another six-year term.

This is true, the analysis states, even in states where the president cruised to reelection.

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In states that went for the president by more than 10 percentage points, the other party’s senator has won reelection in the following midterm more than 90 percent of the time.

Over that period, 43 senators have run for reelection in states the other party’s president won by more than 10 percentage points. Only four — Max Cleland (D-Ga.) in 2002, Al D’Amato (R-N.Y.) in 1998, Howard Cannon (D-Nev.) in 1982 and Edward Brooke (R-Mass.) in 1978 — lost their reelection bids.

Such statistics are of crucial interest given this year’s Senate map, in which 10 Democratic incumbents will run for reelection in states President TrumpDonald John TrumpHannity urges Trump not to fire 'anybody' after Rosenstein report Ben Carson appears to tie allegation against Kavanaugh to socialist plot Five takeaways from Cruz, O'Rourke's fiery first debate MORE won in 2016.

“Every midterm, it’s always good to be the party out of the White House,” said Bruce Mehlman, a Republican lobbyist who analyzed the 333 Senate races that have taken place since 1978 as part of a widely-read quarterly political update to clients.

Five Democratic senators are running for reelection in states Trump won by more than 10 points: Sens. Joe DonnellyJoseph (Joe) Simon DonnellyThe Memo: Tide turns on Kavanaugh McCaskill to oppose Kavanaugh nomination The Memo: Kavanaugh firestorm consumes political world MORE (Ind.), Claire McCaskillClaire Conner McCaskill'Kavanaugh' chants erupt at Trump rally in Missouri The Hill's Morning Report — Sponsored by United Against Nuclear Iran — Kavanaugh, accuser say they’re prepared to testify Drug companies will love Trump's plan to get rid of drug rebates — the consumers will hate it MORE (Mo.) and Heidi HeitkampMary (Heidi) Kathryn HeitkampGOP Senate candidate: Allegations against Kavanaugh 'absurd' The Memo: Tide turns on Kavanaugh McCaskill to oppose Kavanaugh nomination MORE (N.D.) are among the most vulnerable members seeking reelection. Sens. Joe ManchinJoseph (Joe) ManchinCook Political Report moves Texas Senate race to ‘toss-up’ The Memo: Tide turns on Kavanaugh McCaskill to oppose Kavanaugh nomination MORE (W.Va.) and Jon TesterJonathan (Jon) TesterMontana lawmakers cheer recommendation to ban mining north of Yellowstone Cook Political Report moves Texas Senate race to ‘toss-up’ Trump Jr. campaign event looks for new venue after Montana restaurant declines to host MORE (Mont.) are seen as safer bets, though their wins are by no means assured.

Five other Democrats are running for reelection in states Trump won by fewer than 10 points: Sens. Tammy BaldwinTammy Suzanne BaldwinDems seek to rebuild blue wall in Rust Belt contests The Hill's Morning Report — Sponsored by United Against Nuclear Iran — The Hill interviews President Trump Poll: Democrats inch forward in Wisconsin MORE (D-Wis.), Sherrod BrownSherrod Campbell BrownSherrod Brown says he's 'not actively considering' running for president Election Countdown: Trump confident about midterms in Hill.TV interview | Kavanaugh controversy tests candidates | Sanders, Warren ponder if both can run | Super PACs spending big | Two states open general election voting Friday | Latest Senate polls Overnight Health Care: Senators target surprise medical bills | Group looks to allow Medicaid funds for substance abuse programs | FDA launches anti-vaping campaign for teens MORE (Ohio), Bob CaseyRobert (Bob) Patrick CaseyPoll: Democrats hold big leads in Pennsylvania Senate, governor races The Hill's Morning Report — Sponsored by United Against Nuclear Iran — Kavanaugh, accuser say they’re prepared to testify Trump: 'Good news' that Obama is campaigning again MORE Jr. (Pa.), Bill NelsonClarence (Bill) William NelsonPolitical shenanigans mask true problems in Puerto Rico The Hill's Morning Report — Sponsored by United Against Nuclear Iran — The Hill interviews President Trump The Hill's 12:30 Report — Kavanaugh controversy consumes Washington | Kavanaugh slated to testify Monday | Allegations shake up midterms MORE (Fla.) and Debbie StabenowDeborah (Debbie) Ann StabenowCongress prepares to punt biggest political battles until after midterms Trump attacks Dems on farm bill Trump is wrong, Dems are fighting to save Medicare and Social Security MORE (Mich.). Of those five, only Nelson has a top-tier challenger, in Florida Gov. Rick Scott (R).

If history holds, all five of those senators will be back for another six-year term. In the last 10 midterms, no senator seeking reelection from a state the other party’s president won by fewer than 10 percentage points has lost.

Incumbents from the party out of power have a better chance of winning reelection than incumbents from the same party that holds the White House, Mehlman found.

Just about half of members of a president’s party win reelection in states the president did not carry. Over the last 40 years, the incumbent of a president’s party has won reelection in 14 of 27 attempts in a state the president did not carry.

This year, only one Republican — Sen. Dean HellerDean Arthur HellerHeller embraces Trump in risky attempt to survive in November McConnell suggests he could hold Senate in session through October The Hill's Morning Report — Sponsored by United Against Nuclear Iran — Kavanaugh, accuser say they’re prepared to testify MORE (R-Nev.) — falls into that category. But Trump lost Nevada to Hillary ClintonHillary Diane Rodham ClintonFive takeaways from Cruz, O'Rourke's fiery first debate Heller embraces Trump in risky attempt to survive in November Live coverage: Cruz, O'Rourke clash in Texas debate MORE by just 2.5 percentage points, and the incumbent senator has won nearly 69 percent of the time if their party’s president lost by such a narrow margin.

The president’s party has held 80 percent of open seats in states he carried by more than 10 points over the last 10 midterms, but just 31 percent of seats that the president carried by less than a 10-point margin. This year, that means Republicans have a strong chance to retain Sen. Bob CorkerRobert (Bob) Phillips CorkerPoll: More voters oppose Kavanaugh’s nomination than support it Ford opens door to testifying next week Police arrest nearly two dozen Kavanaugh protesters MORE’s (R-Tenn.) seat, but they have a far weaker chance of holding on to Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeGrassley panel scraps Kavanaugh hearing, warns committee will vote without deal Coulter mocks Kavanaugh accuser: She'll only testify 'from a ski lift' Poll: More voters oppose Kavanaugh’s nomination than support it MORE’s (R-Ariz.) seat in a state Trump carried by only 4 percentage points.

“It’s better to be a Democratic incumbent in a state Trump won by more than 10 than a Republican open seat candidate in a state Trump won by less than 10,” Mehlman said.