As of now, Rep. Eric Swalwell has taken 49.2 percent of the 15th Congressional District’s vote with Republican Hugh Bussell 25.9 percent and state Senate Majority Leader Ellen Corbett at 24.9 percent.

And that looks a recipe for Swalwell’s second term.

Bussell, the Alameda County GOP vice chairman from Livermore, leads Corbett, D-Hayward, by only about 600 votes, too small a margin to call which one of them will make it into the top two. In Alameda County, which includes the lion’s share of the district, the registrar still must review and/or count about 64,000 vote-by-mail ballots plus about 8,000 provisional ballots countywide. Likewise, Contra Costa County has as many as 50,000 more ballots to count.

The district’s voters are 48 percent Democrats, 22 percent Republicans and 21 percent nonpartisans. Swalwell, D-Dublin, built a Democrat-nonpartisan bloc – with a few Republicans too, probably – to dominate the middle of the field and crowd Corbett to one side; by drawing almost half the vote, he left her no room to maneuver beyond her liberal, labor-backed, Democratic base.

Bussell seemed happy Wednesday, and rightly so – his share of the vote slightly exceeded his party’s registration. But he’s probably too smart and well-versed to believe in his heart that if he gets to November, he can win.

Few who voted for Corbett will vote for him; they’ll vote either for Swalwell or not at all. And Bussell can expect no monetary aid from the state GOP, the National Republican Congressional Committee or other party entities, who’ll be focused on winnable races; he had about $3,200 cash on hand to Swalwell’s $697,000 as of mid-May.

“It’s a very steep hill to climb,” he acknowledged Wednesday. “On the other hand, as people take notice that there’s a Republican in the race, they may take a closer look at what I stand for … and Eric might find some of his support falling away as well.”

If Corbett edges out Bussell, it’s hard to imagine Bussell voters pivoting to support her instead of Swalwell – she argues Swalwell isn’t liberal enough for the district. And if her support from labor unions only just barely gets her into the top two this week, it’s hard to see how they can suddenly push her to victory in the larger-turnout, less ideological electorate we’ll see in November.

Corbett was enduring the primary cliffhanger stoically Wednesday.

“I called Mr. Swalwell this morning and wished him well and congratulated him in coming in first,” she said. “But we’re just going to have to wait for the votes to be counted … We’ll see how that goes.”

Bussell agreed. “I’m guardedly optimistic. At some level, it’s just fantastic we’re even at this point.”