The GOP resurgence calls to mind the 1966 midterm, another successful year for the party.  RN was a big part of that success, as Warren Weaver wrote in The New York Times on November 13 of that year:

The political equivalent of the batting championship for the 1966 campaign season went to former Vice President Richard Nixon hands down.

During the two months or more that preceded Tuesday’s election, Mr. Nixon specifically stumped for 86 Republican candidates for Governor, Senator and Representative.  When the dust cleared, 59 of them had won for a .686 average.

During this campaign, RN won the gratitude of Republicans across the country and thus created an important base of support for his 1968 bid for the presidency.  Ever since, many would-be presidents have followed the Nixon model by campaigning for their parties’ midterm candidates.  In this election, Sarah Palin has been especially prominent.  Politico quotes Republican consultant Ed Rollins:

Rollins likened Palin’s 2010 push to Richard Nixon’s campaign swing across the country in 1966, when Nixon positioned himself for another presidential run in 1968 after his loss to John F. Kennedy by stumping for congressional candidates nationwide, helping to lift the GOP to a 47-seat gain.

“No one remembers who won or lost, only that he was out there,” Rollins said.

Campaigning in the 1966 midterm was only one part of RN’s long-term strategy for the 1968  race.  He burnished his foreign-policy credentials with extensive international travel and intensive study of global affairs.  One product of his labors was his well-regarded 1967 Foreign Affairs article, “Asia After Vietnam.”  The Supreme Court was to be a significant issue in the presidential race, and he enhanced his credibility by arguing a case before the Court, Time v. Hill.