Washington TV insiders are leaning toward NBC White House reporter David Gregory as the likely long-term replacement for Tim Russert on Sunday's Meet the Press. Russert's successor has been the hot topic in media circles ever since he died June 13 after suffering a heart attack. Sources close to the peacock network say Gregory has the lead on others itching for the post. The reasons: He's shined as a sometimes host on the Today Show, has his own election show on MSNBC, and has a strong following. "I'd look to see if they start making changes on his show as an indication he's got it," says a TV exec. The tall Gregory, called "Little Stretch" by the president, hosts Race for the White House. Meanwhile, sources close to former Nightline host Ted Koppel say he isn't interested in working weekends.