How has an unpopular Presidential Candidate affected congressional races?

Politics & Elections
1

How have congressional races played out when unpopular candidates were at the top of the ticket?

Aside from the outcome, I wonder how it affected the campaigns themselves.

I recall some Democratic candidates pivoting away from Obama in 2012 over Obamacare, and if memory serves they were not generally rewarded for this, but that is over one specific issue not overall unpopularity.

2

Here is an example : in 2004 when John Edwards was the VP pick with Kerry he came back to Raleigh for a rally. Almost all the Dems in state politics and US house stayed away from the rally because they did not want to be tied to Edwards and Kerry. Bush easily won NC in 2000 and 2004. Obama won here in 2008 by less than 1% but lost in 2012.