California's new top-two primary differs from its nonpartisan elections in one significant respect.

In campaigns for city and county offices, as well as for state superintendent of public instruction, a candidate can win outright in the primary by garnering a majority of the votes. That isn't the case with the top-two system that gets its first test in the June 5 primary.

The top two finishers in primaries for the U.S. Senate, the House of Representatives and the state Legislature will advance to the general election, regardless of their party affiliation and regardless of the margin of victory.

Of those contests, the most lop-sided almost certainly will be the one for the U.S. Senate. It's also the most crowed race, at least on local voters' ballots, with Democrat Dianne Feinstein and 23 other candidates, all of whom can charitably be described as unknowns and long-shots.

In one recent poll, Feinstein was backed by more than 50 percent of voters while the two next highest — businessman Dan Hughes and nonprofit executive Elizabeth Emken — had 2 percent apiece.

Feinstein was elected to the Senate in 1992, and she has been re-elected three times. If she ever was going to be vulnerable to a challenge, it was this year, when she turns 79, voters disgust with Congress is high, and about $4.5 million was embezzled from her campaign treasury. Yet, in a reprise of the 2006 election, the GOP failed to recruit a top-tier challenger. That's a stark contrast to 2010, when ex-Hewlett-Packard CEO Carly Fiorina was defeated by Sen. Barbara Boxer.

All things considered, it's not so surprising that Feinstein seems to have an easy path to re-election. During her two decades in Washington, the former San Francisco mayor has cultivated support across the political spectrum.

Her legislative portfolio includes securing a federal ban on assault weapons after the 101 California Street massacre in 1993 (though congressional Republicans allowed it to expire 10 years later). She has worked closely with growers and environmentalists on water and energy issues, introduced legislation to crack down on predatory lawsuits, and she's the first Californian to chair the Senate Intelligence Committee.

"If you have a business in California and you need to get something moved through Congress, you go to Dianne Feinstein," Bill Whalen, a Republican research fellow at Stanford's Hoover Institution, told the Sacramento Bee. "Feinstein can go to Republicans and work with them; she is far more centrist than most Democrats in that chamber."

At a time when Washington's most glaring problem is an inability to set aside partisan differences for the common good, Feinstein is more interested in finding solutions than scoring cheap political points.

That's a solid endorsement for any politicians. We're not ready to tinker with the top-two primary system, but this year's Senate contest offers voters a chance to participate in a display of nonpartisan unity by returning Dianne Feinstein to the U.S. Senate. You can start by supporting her on June 5.