IN ONE of the great turnarounds of the last month, Richard L. Thornburgh (R), 46, former Pittsburgh prosecutor and Justice Department official, has finally made a race of his battle for governor with former Pittsburgh mayor and deputy attorney general Pete Flaherty (D), 54. The winner will succeed retiring Gov. Milton J. Shapp (D). Lagging badly in early October, Thornburgh hammered in TV ads at Flaherty's claimed reductions in public jobs and taxes in Pittsburgh, and did everything possible to link the anti-Shapp mayor to the scandal-tainted state administration. Flaherty, who disdains a formal campaign organization, was slow to react until the last few days, letting the race narrow to a few points' difference. A big Philadelphia turnout on a charter revision to allow Mayor Frank Rizzo a third term would normally help the Democrats, but Thornburgh has an unusual degree of black support. No longer a sure Democratic win, this race may not be far from a tossup.

Two representatives are seeking reelection while under indictment. Rep. Daniel J. Flood (D) is almost certain to win and a sympathy reaction among some constituents could help Rep. Joshua Eilberg (D) stave off what has seemed a likely defeat by state Sen. Charles F. Dougherty (R). Rep. Joseph S. Ammerman (D), whose auto accident injuries kept him from campaigning for weeks, could lose his seat, but Rep. Robert W. Edgar (D), the other vulnerable Democrat in traditional GOP territory, is a narrow favorite. Democrats should hold both their open House seats and are favored to win the seat of retiring Rep. Gary A. Myers (R).