Still bad for Democrats with their disarray. Nixon's paranoia about Muskie was just that, paranoia. He could use Muskie's clout as an environmental law champion to hurt him with organized labor in natural resources industries, i.e. West Virginia's gone, blast him for his very public support of black power, and levy anti-Catholic sentiment. You're right about the Polish vote though, and that with a more industrial labor-friendly campaign probably gets him Wisconsin and Michigan.
President Richard Nixon (R-CA) / Vice President Spiro Agnew (R-MD) ✓
Senator Edmund Muskie (D-ME) / Senator Fred Harris (D-OK)