Republican control of both the House and Senate would provide Mrs. Clinton a clearer target to run against in courting voters fatigued by Washington dysfunction. The longer an unpopular president and his more-unpopular partisan adversaries battle to a standstill, the easier it is to offer herself as a fresh start.

“It would be bad for the country,” said Stanley B. Greenberg, President Bill Clinton’s former pollster, but “total gridlock would allow Hillary to be the change.”…

In the last 60 years, only George Bush managed to capture a third straight presidential victory for his party. He did it in 1988 — two years after the Democratic opposition had regained unified control of Congress by retaking the Senate in midterm elections.