Why were downballot dems so resilient in the 70s and 80s compared to presidential nominees?

[Matty]

1968-1992 was a golden age of republican politics on the national level, but downballot, dems fared much better.

What explains why american voters turned on the dems in presidential politics, but continued to support them in other races?

[Benjamin Frank]

The two general explanations put out at the time:

"All politics is local" Speaker of the House Tip O'Neill

"Americans are ideologically conservative but operationally liberal."  Political operative Mark Shields (when he was in his prime, not the sad person he was towards the end on the PBS News Hour.)

[TML]

It may take time for voting patterns at the top of the ticket to filter through downballot. Back in the early 1970s, George McGovern predicted that the South would become solidly Republican in the aftermath of the Civil Rights movement. He was right, although it did take over four decades in some cases for Republican strength to filter through downballot.

[Schiff for Senate]

Honestly, Democratic incumbents were more charismatic and were very popular personalities in their states in many cases.

Also, most of the south was still represented by Democrats/Dixiecrats. These southern Democrats were honestly more conservative than the vast majority of today's Democrats, but they helped keep the House blue for 40 consecutive years.