The Link Between Senate and Presidential Voting

After seeing a lot of people predict that Ben Nelson and Scott Brown will lose because of their states’ respective presidential voting patterns, I was reminded of a section of one of my political science textbooks from last semester. In Chapter 6 of The Politics of Congressional Elections, the author, Gary Jacobson, details the events leading up to each set of congressional elections from 1980 to 2006 as well as the overall results. One thing I found particularly interesting at the time was that the percentage of Senate seats won by the party of the presidential candidate that also won that state has been on the rise over the past decade. Here are the relevant passages from page 218-219 of the book:

The same trend toward greater consistency in voting for president and U.S. representative in 2004 (Figure 6-3) appeared in Senate elections as well, resulting in a four-seat addition to the Republicans’ Senate majority. . . The Democrat’s main problem was again structural. They had to compete with the more-efficient distribution of Republican voters. Although Gore had won the national vote in 2000, Bush carried thirty of the fifty states, including twenty-two of the thirty-four states with Senate contests in 2004. Democrats had to defend ten seats in states Bush had won, including five left open by retirements, all in the South, where support for Democrats has been eroding for several decades. Meanwhile, Republicans were defending only three seats in states won by Gore. . . Seven of the eight Senate seats that changed party hands in 2004 went to the party that won the state in the 2000 and 2004 presidential elections; Salazar’s victory was the lone exception. . . More generally, twenty-seven of the thirty-four Senate contests were won by the party whose presidential candidate won the state’s electoral votes, tying 1964 for the highest level of congruence in president-Senate election results in the past half century. When the 2004 winners were added to the continuing Senate membership, fully 75 percent of Senators represented states where their party’s candidate won the most recent presidential election, the highest proportion in at least fifty years.

So what does this mean for the parties going into 2012. More below the fold.

In 2012, Democrats have 23 Senate seats up for election. These are listed below and the states in bold were won by McCain in 2008.

Democratic-Held Senate Seats

California

Connecticut

Delaware

Florida

Hawaii

Maryland

Michigan

Minnesota

Missouri

Montana

Nebraska

New Jersey

New Mexico

New York

North Dakota

Ohio

Pennsylvania

Rhode Island

Vermont

Virginia

Washington

West Virginia

Wisconsin

In contrast, Republicans only have 10 seats up in 2012. These are listed below and the states in bold were won by Obama in 2008.

Republican-Held Senate Seats

Arizona

Indiana

Maine

Massachusetts

Mississippi

Nevada

Tennessee

Texas

Utah

Wyoming

So right away you can see that each party holds Senate seats that would tend to go to the opposite party given normal conditions. Republicans should win Missouri, Montana, Nebraska, North Dakota, and West Virginia while Democrats should pick-up Indiana, Maine, Massachusetts, and Nevada. That works out to +1 R even after removing West Virginia and Indiana which are not likely to flip unless something dramatic happens such as Lugar losing to a Tea Party challenger in the primary. Maine is harder to judge, though I predict Snowe would win if she survives a primary challenge, bumping Republicans to +2.

One problem with this analysis is that it is based on the results of the 2008 elections because I can’t see the future and tell you who will win each state in 2012. Some speculation is possible though based on the results from 2008 and recent polls. The only Republican-held seat won by McCain that Obama has a realistic chance of winning is Arizona which he lost by 8.5%. Arguments can be made for Texas or maybe Tennessee but that’s unlikely barring a Regan vs. Mondale type wave. Obama also has a chance at winning Missouri (lost by 0.13%), Montana (lost by 2.38%), and North Dakota (lost by 8.65%) which would increase the chances of holding these Democratic Senate seats.

The Republican presidential candidate could win states with Democratic-held seats in Virginia (lost by 6.3%), Florida (lost by 2.81%) and Ohio (lost by 4.58%). Other states that seem less likely to flip right now but could depending on the environment include Pennsylvania (lost by 10.31%) and Michigan (lost by 16.44%). States that McCain lost last time but may be won by the Republican presidential candidate in 2012 include Indiana (lost by 1.03%) and possibly Nevada (lost by 12.49%). Winning back these states would increase the chance that Republican incumbents could hold their seats.

So where does all of this leave us? Here are three scenarios.

1. Obama wins all of his 2008 states and most Senate seats go with the presidential winner that state – R+1 or 2

Democrats pickup Massachusetts and Nevada, possibly Maine, and fail to pickup Indiana.

Republicans pickup Missouri, Montana, Nebraska, and North Dakota and fail to pickup West Virginia.

2. Obama improves on his 2008 map and most Senate seats go with the presidential winner in that state – D+2 or 3

Democrats pickup 4 or 5 of Arizona, Indiana, Maine, Massachusetts, and Nevada.

Republicans pickup Nebraska and North Dakota and fail to pickup West Virginia.

3. Obama does worse than his 2008 map and most Senate seats go wi the presidential winner in that state – R+2 to 8

Democrats pickup 0 to 2 of Massachusetts and Nevada and fail to pick up Maine.

Republicans pickup 4 to 8 of Florida, Michigan, Missouri, Montana, Nebraska, North Dakota, Ohio, Pennsylvania, Virginia, and West Virginia.

Senate Democrats’ best chance at keeping their majority involves Obama expanding the playing field and it appears this is the plan after Charlotte was chosen to be the site of the DNC. With the continued polarization of electorate, it may not be possible for vulnerable senators like Tester, McCaskill, Webb, and Brown to localize the election in hopes of drawing crossover support. This could certainly help their chances but the trends over the last decade indicate that their electoral survival depends heavily on the President.

 Loading ...