Democrats in three key Senate races posted weekend poll gains -- two of them indicating possible turnarounds and the other a possible slam-dunk. In Pennsylvania, Sen. Harris Wofford, who'd been more than 10 points down last month, pulled even with or ahead of GOP challenger Rick Santorum (44-43 according to the Greensburg Tribune-Review, 45-41 by KDKA-TV, 36-34 The Harrisburg Patriot-News). The 68-year-old Wofford's been hammering at Santorum's recent suggestion that the Social Security retirement age be raised to 70 . . . InVirginia, Sen. Chuck Robb, dead even with Republican nominee Oliver North last week, was up 8 points (39-31, from The Richmond Times-Dispatch) or still even (37-36, form the Fairfax Journal) . . . In California, Sen. Dianne Feinstein is now poised to trounceGOP Rep. Michael Huffington, running well ahead in two polls (52-36, from the San Francisco Examiner; 48-38, from KCAL-TV), though trailing in another (42-40, KCBS-TV).Post your opinion on theElection '94bulletin board.