Spending in the special election to replace former Rep. Ellen Tauscher (D-Calif.) has already topped $1.5 million and seems destined to break the $2 million mark, according to campaign finance reports released late Thursday.

Through Aug. 12, the five top candidates in the all-party primary had collectively spent more than $1.5 million.

Lt. Gov. John Garamendi (D) had raised the most money, both in the latest fundraising period and overall. He took in $217,000 from July 1 to Aug. 12, and he collected $517,000 in the special election.

State Sen. Mark DeSaulnier (D) reported raising $184,000 since July 1, including a $15,000 loan he gave his campaign, and he raised $395,000 since the start of the campaign.

State Assemblywoman Joan Buchanan (D) reported the highest amount of receipts, both since July 1 and overall, but those figures were buttressed by $500,000 of her own money. Including the loans, she took in $281,000 from July 1 to Aug. 12, and $595,000 overall.

Iraq War veteran Anthony Woods (D) had raised $109,000 since July 1, and $214,000 for the entire campaign. Attorney David Hamer, the leading Republican in the race, raised $74,000 for the reporting period and $250,000 total.

As of Aug. 12, Garamendi had the most cash in reserve, $133,000, followed by DeSaulnier with $108,000.

A dozen candidates from all parties will appear together on a primary ballot on Sept. 1. If, as expected, no candidate tops 50 percent, the top vote getters from each party will advance to a general election on Nov. 3. Because Tauscher’s East Bay district is so heavily Democratic, the Democrat who finishes first in 11 days is almost certain to advance to Congress.

Garamendi, the best-known candidate in a broad sense, has topped two recent polls, and the other Democrats are beginning to take their shots. DeSaulnier has begun reminding voters that Garamendi does not live in the 10th district and cannot vote for himself, even though he owns ranchland that borders on the district.

Because turnout is expected to be so low — there are no other contests on the ballot on Sept. 1 — it is hard to predict who will go to the polls and how they will vote. If name recognition alone were the predictor, Garamendi would almost certainly win.

But DeSaulnier has locked up a number of significant grass roots groups and unions; Buchanan is hoping to score points by emphasizing, as her TV ad says, that she’s “not one of the boys.— And Woods, who is best known for challenging the “don’t ask, don’t tell— policy for gays serving in the military, is trying to tar his opponents with their ties to state government.

Buchanan, DeSaulnier and Garamendi have all been on the air with TV ads for several days and will stay there until the primary.

The 10th district seat is open because Tauscher took a top job at the State Department.