Why did Democrats lose most of the close Senate races in 1992?

[Mr.Phips]

Going into election day 1992, it looked like there was a good chance of Democrats gaining the three Senate seats needed to get 60 votes in the Senate.  They held poll leads in all of their own seats and in three Republican seats, which were California (Seymour), Wisconsin (Kasten), and New York (D'Amato).  This would have gotten Dems to 60 seats.  Democrat John Rauh even led in some of the polls for Warren Rudman's old seat in New Hampshire and were only barely behind in Oregon (Packwood) and Pennsylvania(Spector).

Based on polls and the fact that they were working with a good political environment (Clinton was winning easily), Dems were the favorites to.get to at least 60 votes.

However, on election day, they only picked up California and Wisconsin and ended up losing North Carolina and Georgia(in the runoff later in the month) despite leading in virtually all polls.  Even Al D'Amato won in New York despite Clinton winning there by over 20 points and D'Amato trailing in all polls.

What happened?