The outcome of the 2009 campaign for Governor of New Jersey is not historically significant to Barack Obama's presidency. It is almost twice as likely that New Jerseyans elect a governor who is not a member of the president's party. Indeed, the party of the incumbent president is 15-26 in New Jersey gubernatorial races since a Democrat won in Abraham Lincoln's mid-term election.
The last five gubernatorial elections went that way: Republicans lost in 1989 (George H.W. Bush), 2001 and 2005 (George W. Bush), and Democrats lost in 1993 and 1997 (Bill Clinton). But in the seven contests before that, the party of the sitting president went 6-1: Republicans won in 1969 (Richard Nixon), 1981, and 1985 (Ronald Reagan), and Democrats won in 1961 (John Kennedy), 1965 (Lyndon Johnson), and 1977 (Jimmy Carter); Republicans lost in 1973, after the incumbent was defeated in the primary and in an election that was held under the backdrop of the Watergate scandal.
None those twelve campaigns influenced the outcomes of the next presidential campaign, either nationally or in pursuit of New Jersey's electoral votes – although the 1973 results were a harbinger of the 1974 Democratic landslide. By 1976, New Jersey was supporting a Republican presidential candidate.
Democrats won both gubernatorial elections held during Dwight Eisenhower's presidency, and Republicans won both governors' races held while Harry Truman was president. During the four campaigns for governor that occurred during Franklin Roosevelt's tenure in the White House, Democrats won two (1937 and 1940) and lost two (1934 and 1943). Eisenhower carried New Jersey twice, and Roosevelt won the state four times.
Republicans lost a race during Herbert Hoover's term, won one and lost one under Calvin Coolidge, and lost one under Warren Harding. But Republicans won two under Theodore Roosevelt and two under William McKinley.
Truman, Hoover and William Howard Taft (1910/1912) lost New Jersey when they ran for second terms after their parties lost gubernatorial races.
During the three gubernatorial elections held while Woodrow Wilson, a former governor, was president, Democrats won one and lost two. Democrats won one (1886) and lost one (1895) during the presidencies of Grover Cleveland, a New Jersey native.
Before Cleveland, the party in the White House lost seven races for governor of New Jersey. (This analysis does not include the presidency of Andrew Johnson, a Democrat elected Vice President on Lincoln's ticket in 1864. Republicans won the governorship in 1865 and lost in 1868.)