Dan Roberts can do the math.
The stockbroker from Tiburon, one of 12 candidates for the North Coast congressional seat, knows that support from fellow Republicans isn't enough in the June 5 primary election.
"I need 3 to 5 percent of the Democrats to come my way," he said.
Republicans are outnumbered more than 2-to-1 by Democrats among registered voters in the six-county 2nd Congressional District stretching from Marin to the Oregon border, and hold a base of less than 30 percent of the vote.
Roberts, a political newcomer who has loaned his campaign $160,000, probably had a chance at finishing second — and advancing to the November runoff election — until Michael Halliwell of Cotati, unsuccessful in three previous bids for Congress, registered for a fourth race.
In the 2010 Republican primary, Halliwell got 32 percent, limiting the winner, Jim Judd of Rohnert Park, to 68 percent.
Roberts, 69, a Vietnam War veteran, might appeal to moderate Democrats by advocating an immediate withdrawal from Afghanistan "to halt the loss of life and limb" and the "drain on our national treasury."
But he is otherwise in step with GOP orthodoxy, saying the nation "can't spend or borrow our way out of the malaise we're in" and advocating elimination of the Energy and Education departments and the Environmental Protection Agency.
If a liberal Democrat wins the North Coast seat, "we're going to live with them for years and years," he said.
Roberts and Halliwell are among the eight long-shot candidates in the race, which has no incumbent.
Democrat Andy Caffrey of Garberville, a lifelong activist and organizer, puts the "climate crisis" foremost among the issues, saying at a candidates forum in February, "There are no jobs on a dead planet."
"The task of our time is to get citizen leaders elected," he said in an interview, because members of Congress "are not going to do anything."
Larry Fritzlan, a Democrat and therapist from Mill Valley, insists that "politics is poisoned" by the influence of money and the "massive corruption of Congress."
Democrat William Courtney of Mendocino, describes himself as a "cannabis physician" and says marijuana could be a lucrative legitimate industry and the basis for a heart attack remedy.
John Lewallen, a seaweed harvester from Philo, espouses a liberal platform — end the war, legalize marijuana and establish single-payer health care — as a no-party-preference candidate on a campaign budget of about $5,000.
Three others — Halliwell, Fritzlan and Brooke Clarke of Ukiah, also a no-party-preference candidate — reported no campaign funding.
Clarke, a small business owner, advocates electing independents like himself because Democrats and Republicans are the same on "big issues."
Democrat Tiffany Renee, vice mayor of Petaluma, said she was obliged to scale back her fundraising to about $15,000 and still hopes to follow Rep. Lynn Woolsey's leap from the Petaluma council to Congress.
"I think this race is still very wide open," said Renee, who said she would be the ninth Latina elected to the House.
You can reach Staff Writer Guy Kovner at 521-5457 or email@example.com.