I mean, a fair way to measure how a president expanded a party's coalition is if he carried a state that went for the other party in the previous election, and stayed with his party until the present day. For example, George W. Bush definitely brought Arkansas into the Republican coalition. In 1996, it voted Democratic, but Bush flipped it, and it's remained GOP ever since.
By that standard, for the Democrats, we have-
Johnson 1964 - DC (3 present-day electoral votes) total: 3
Carter 1976 - MN (10) total: 10
Dukakis 1988 - MA (11), RI (4), NY (29), WI (10), WA (12), OR (7), HI (4) total: 77
Clinton 1992 - ME (4), VT (3), CT (7), NJ (14), PA (20), DE (3), MD (10), MI (16), IL (20), CA (55) total: 152
Obama 2008 - VA (13), FL (29), OH (20), IA (7), CO (9), NM (5), NV (6), NH (4) total: 92
The Clinton transformation clearly is what this country competitive for two parties again.
Minnesota was already solidly Democratic having only yielding to GOP for Eisenhower. A case for
Truman or
Kennedy? Maybe
But to claim Carter brought Minnesota in is just laughable,...Carter won an artificial victory with the last of old coalitions.