Paul -- an eye surgeon and son of Rep. Ron Paul, R-Texas -- will be the GOP nominee in November in the race to determine who will succeed another Republican, the retiring Sen. Jim Bunning, the Lexington (Ky.) Herald-Leader reported. He handily defeated Kentucky Secretary of State Trey Grayson, drawing 59 percent of the vote with 42 percent of the ballots counted, NBC News said.
Grayson had the backing of establishment Republicans, including Senate Minority Leader Mitch McConnell of Kentucky.
The contest in Kentucky was one of several key primary races in three states Tuesday that could provide a yardstick about the depth of anti-incumbent, anti-Washington sentiment among voters.
Democrats and Republicans alike were watching crucial elections in Pennsylvania and Arkansas as well, to see how well party mainstream candidates do, because their success could be a harbinger of things to come in the fall.
In Pennsylvania, five-term Sen. Arlen Specter, seeking the Democratic nod in his re-election bid, was in a battle with U.S. Rep. Joe Sestak in a race polls determined was race that is too close to call. Specter, who left the Republican Party last year, has the backing of President Barack Obama, Vice President Joe Biden, Pennsylvania Gov. Edward G. Rendell and much of the Democratic establishment. Sestak, however, has run a campaign that, among other things, painted Specter as an opportunist who changed parties to save his political career.
Pennsylvanians in the 12th Congressional District voted in a special election for a person to finish the unexpired term of Rep. John Murtha, a Democrat, who died in February. Many political observers say this race could provide a glimpse of what to expect in November. Voters in the 12th Congressional District also voted in their respective party primaries for Murtha's seat in the next Congress.
Sen. Blanche Lincoln, D-Ark., has had a target painted on her back by both Democrats and Republicans. She faced a tough primary challenge from the left by Lt. Gov. Bill Halter, who has depicted her as an inside-the-beltway denizen while asserting he is a change-agent backed by some powerful unions. While leading in the polls, observers note Lincoln may not reach the crucial 50 percent threshold to avoid a runoff in June.
Republicans, meanwhile, look at Lincoln's seat as theirs for the taking on Election Day. Real Clear Politics lists Lincoln's seat as "Likely Republican."
Primaries were also held in Oregon Tuesday. Republican voters must winnow a crowded field to the person who likely will face incumbent Sen. Ron Wyden, who faced two challengers on the Democratic ballot.
While Obama has stumped little for Specter or Lincoln -- although he did have a flyover in Pennsylvania and cut an ad for Lincoln -- White House spokesman Robert Gibbs said Monday "everyone knows ... who we support in those two races."
"We have supported incumbent Democratic senators and we've done a lot on behalf of each campaign," Gibbs said during a daily media briefing. "Again, there are races all over the country that we'll have a chance to look at from a Democratic and Republican side as to what it means."