(AP) — A Georgia congressional election in a historically conservative district is headed to a runoff that raises the stakes in an early measure for President Donald Trump and both major parties ahead of the 2018 midterm elections. The winner will succeed Republican Tom Price, who resigned the seat to join Trump's administration as health secretary. Leaders in both major parties agree the race offers a prime test run for 2018 elections, because the affluent, well-educated Georgia district is replete with the kind of voters Democrats must attract to reclaim a House majority and win more gubernatorial and Senate races. Trump, who took to social media in the campaign's closing days to heckle Ossoff and encourage Republicans, crowed on his personal Twitter account: Despite major outside money, FAKE media support and eleven Republican candidates, Big 'R' win with runoff in Georgia. [...] Trump gave Ossoff his opening in the first place. Ossoff has capitalized on anti-Trump energy while still trying to appeal to independents and moderate Republicans — his only path to victory. A political action committee backed by Ryan and other House GOP leaders funneled more than $2 million into attacks on Ossoff, tying him to national Democrats like House Minority Leader Nancy Pelosi.