Ellen Corbett, who is leaving the state Senate because of term limits and trying to win a congressional seat, says incumbent Rep. Eric Swalwell doesn't understand his East Bay district as well as she does.

Actually, it's just the opposite. It was Swalwell, then an Alameda County prosecutor and Dublin city councilman, who recognized two years ago that predecessor Pete Stark was out of touch with his constituents and an embarrassment to his colleagues.

It was Swalwell who recognized the district wanted a well-reasoned and thoughtful representative and had the background, tenacity and intellect to take on a 20-term incumbent and unseat him.

Since then, Swalwell has demonstrated that he wasn't merely an alternative to Stark but is also a hardworking congressman who has admirably represented his constituents. He deserves another term.

The third candidate in this race, Hugh Bussell, lacks political experience, demonstrates confusion about key issues and seems to be only a place holder Republican alternative.

This campaign focuses on the two Democrats, Swalwell and Corbett. In the 15th District, which stretches from Livermore and San Ramon to the north end of Fremont, registration is 48 percent Democratic, 22 percent Republican and 21 percent independent. Thus, Democratic candidates cannot ignore the political middle.

Yet Corbett complains that Swalwell is not left-wing enough for the district. That strategy worked under the state's partisan primary system that helped keep Stark in office 40 years. Previously, in a district like this, a Democrat could appeal to solid partisans to win the primary and then coast in the general election because moderate Democratic voters had nowhere else to go.

But voters mandated the state shift in 2012 to an open primary, in which the top two finishers regardless of party compete in the general election. Suddenly Stark was vulnerable as the more moderate Swalwell appealed to Democrats, independents and Republicans.

Now Corbett wants to bring the district back to heavily partisan representation -- under the guise that she's more in touch with the district. She isn't.

For example, while Swalwell had the good sense not to meddle in the BART strike last year, Corbett swooped in on behalf of her union backers, pressuring transit district management and directors to settle. The eventual deal was a financial disaster for the transit district.

On the state's foolish high-speed rail plan, Corbett voted to keep wasting money on the project, while Swalwell vows to oppose more federal funding unless promised private money materializes.

This district deserves a discerning Democrat. That's why Swalwell is the best choice.