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 TrumpBill Kristol resurfaces video of Pence calling Obama executive action on immigration a 'profound mistake' ACLU says planned national emergency declaration is 'clear abuse of presidential power' O'Rourke says he'd 'absolutely' take down border wall near El Paso if he could 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 DonnellyOvernight Energy: Trump taps ex-oil lobbyist Bernhardt to lead Interior | Bernhardt slams Obama officials for agency's ethics issues | Head of major green group steps down Trump picks ex-oil lobbyist David Bernhardt for Interior secretary EPA's Wheeler faces grilling over rule rollbacks MORE (Ind.), Claire McCaskillClaire Conner McCaskillMcCaskill: Lindsey Graham 'has lost his mind' Trey Gowdy joins Fox News as a contributor The Hill’s 12:30 Report: Trump AG pick Barr grilled at hearing | Judge rules against census citizenship question | McConnell blocks second House bill to reopen government MORE (Mo.) and Heidi HeitkampMary (Heidi) Kathryn HeitkampOvernight Energy: Trump taps ex-oil lobbyist Bernhardt to lead Interior | Bernhardt slams Obama officials for agency's ethics issues | Head of major green group steps down Trump picks ex-oil lobbyist David Bernhardt for Interior secretary On The Money: Shutdown Day 27 | Trump fires back at Pelosi by canceling her foreign travel | Dems blast 'petty' move | Trump also cancels delegation to Davos | House votes to disapprove of Trump lifting Russia sanction MORE (N.D.) are among the most vulnerable members seeking reelection. Sens. Joe ManchinJoseph (Joe) ManchinSenate confirms Trump pick William Barr as new attorney general GOP wants to pit Ocasio-Cortez against Democrats in the Senate Senate poised to confirm Trump’s attorney general pick MORE (W.Va.) and Jon TesterJonathan (Jon) TesterGOP braces for Trump's emergency declaration Border talks stall as another shutdown looms Mulvaney: Government shutdown on the table 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 offer smaller step toward ‘Medicare for all' Overnight Health Care — Sponsored by America's 340B Hospitals — Powerful House committee turns to drug pricing | Utah governor defies voters on Medicaid expansion | Dems want answers on controversial new opioid Why does the bankruptcy code discriminate against disabled veterans? MORE (D-Wis.), Sherrod BrownSherrod Campbell BrownShep Smith: Signing funding bill is a 'loss' for Trump no matter how it's packaged Exclusive: Biden almost certain to enter 2020 race Tim Ryan ‘seriously considering’ 2020 bid MORE (Ohio), Bob CaseyRobert (Bob) Patrick CaseyGOP wants to pit Ocasio-Cortez against Democrats in the Senate Biden speaking to Dems on Capitol Hill as 2020 speculation mounts: report GOP senators: Trump should not declare border emergency during State of the Union MORE Jr. (Pa.), Bill NelsonClarence (Bill) William Nelson2020 party politics in Puerto Rico There is no winning without Latinos as part of your coalition Dem 2020 candidates court Puerto Rico as long nomination contest looms MORE (Fla.) and Debbie StabenowDeborah (Debbie) Ann StabenowThe Hill's Morning Report - Presented by the American Academy of HIV Medicine - Will there be any last-minute shutdown drama? Overnight Health Care — Sponsored by America's 340B Hospitals — Utah tests Trump on Medicaid expansion | Dems roll out Medicare buy-in proposal | Medicare for all could get hearing next month | Doctors group faces political risks on guns Dems offer smaller step toward ‘Medicare for all' 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 HellerTrump suggests Heller lost reelection bid because he was 'hostile' during 2016 presidential campaign Trump picks ex-oil lobbyist David Bernhardt for Interior secretary Oregon Dem top recipient of 2018 marijuana industry money, study finds MORE (R-Nev.) — falls into that category. But Trump lost Nevada to Hillary ClintonHillary Diane Rodham ClintonO’Rourke heading to Wisconsin amid 2020 speculation The Hill's 12:30 Report — Presented by Kidney Care Partners — Lawmakers scramble as shutdown deadline nears Exclusive: Biden almost certain to enter 2020 race 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 CorkerSasse’s jabs at Trump spark talk of primary challenger RNC votes to give Trump 'undivided support' ahead of 2020 Sen. Risch has unique chance to guide Trump on foreign policy MORE’s (R-Tenn.) seat, but they have a far weaker chance of holding on to Sen. Jeff FlakeJeffrey (Jeff) Lane FlakeTrump suggests Heller lost reelection bid because he was 'hostile' during 2016 presidential campaign Live coverage: Trump delivers State of the Union Sasse’s jabs at Trump spark talk of primary challenger 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.