With about 70 percent of registered Democrats expected to participate in today’s Oregon presidential primary, two Democratic Congressional candidates are looking to thumb their noses at the party establishment and pull off upsets.

In the Democratic Senate primary, attorney Steve Novick is locked in a tight race with state Speaker Jeff Merkley, the hand-picked candidate of the Democratic Senatorial Campaign Committee to take on Sen. Gordon Smith (R) in November. In the open 5th district Democratic primary, former gubernatorial aide Steve Marks faces a tougher assignment, but he is still in the mix against state Sen. Kurt Schrader, the unofficial favorite of the Democratic Congressional Campaign Committee.

Smith has a clear path to his party’s nomination — although that didn’t stop him from running a series of television ads over the past three weeks that included spots critical of both Merkley and Novick. In the 5th district Republican primary, 2006 nominee Mike Erickson appeared headed to victory over former state GOP Chairman Kevin Mannix, but a flap over abortion might have changed the course of that race.

Oregon is a vote-by-mail state, and the outcome of these three primaries could be determined not just by who voted, but when votes were cast. Ballots began arriving in voters’ mailboxes around May 3, and voting is usually heaviest during the first and final weeks of the election. Primaries in the Beaver State are closed, and independents are prohibited from weighing in.

The heavy turnout among Democrats, motivated by the first competitive presidential primary in the state in 40 years, is expected to skew the results of the Senate primary, although the Merkley and Novick campaigns differed on how. As of noon Monday, 38 percent of registered voters had participated in the election, including 50 percent of enrolled Democrats and 36 percent of Republicans, according to the Oregon secretary of state.

“It’s been a challenge to compete and grab attention,” said Jake Weigler, Novick’s campaign manager. “That’s why we’re seeing so many undecideds in the [Senate] race. People are focused on the presidential race to exclusion of other races on the ballot.”

The Merkley campaign said the elevated turnout means more Democrats will have voted for the state Speaker in the primary than would otherwise have been the case, and therefore, more voters will be invested in his victory come the fall.

But some observers of the race believe the higher turnout could benefit Novick, as he’s perceived as the outsider who is running as the “change” candidate in a year when voters are hungering for a break with the status quo. The Novick campaign certainly thinks so, noting that polling showed the Portland attorney with an early lead among likely voters who were closely following the race.

But the Merkley campaign argued its candidate’s institutional support — which includes that of several labor unions and Gov. Ted Kulongoski (D) — would only be strengthened by high turnout.

“It means really great things for us and really bad things for Smith,” Merkley campaign spokesman Matt Canter said.

Merkley, clearly the better funded of the two candidates, should benefit from the higher television visibility he was able to afford, not to mention two Democratic Senatorial Campaign Committee ad buys made to buttress his candidacy. Particularly because the Democratic presidential contest between Sens. Hillary Rodham Clinton (N.Y.) and Barack Obama (Ill.) has so saturated political media coverage, Merkley’s television advantage could be crucial to the outcome of the Senate primary.

However, the most recent survey data available continued to show Novick with a narrow lead, with a significant portion of undecided voters.

According to a Public Policy Polling survey conducted Saturday and Sunday, Novick led Merkley 38 percent to 33 percent, with 19 percent undecided. The poll of 1,296 likely voters had an error margin of 2.7 points. In a Survey USA poll, Novick led Merkley 37 percent to 34 percent. That auto-dial poll had an error margin of 4 points.

One interesting player in the Democratic primary has been Smith. His campaign spokesman, R.C. Hammond, said the Senator decided to fight back after going a year without responding to public pummeling from Merkley, Novick and other Democrats.

After first going up with a positive spot on his pledge to work with Democrats in Washington, D.C., Smith pivoted to an ad critical of Merkley and Novick, before progressing to a third television ad and two radio spots that exclusively hammered Merkley.

Canter accused Smith of pulling a “Gray Davis,” saying the Senator views Novick as a weaker general election opponent than Merkley.

Davis, running for re-election as governor of California in 2002, spent $10 million on television ads that ran during a competitive GOP gubernatorial primary campaign. The ads targeted then-Los Angeles Mayor Richard Riordan, seen as Davis’ strongest potential Republican challenger, and they worked. Little-known financier Bill Simon Jr., a political novice, won the GOP primary and went on to lose to Davis in the fall.

Hammond insisted that the timing of Smith’s critical ads was strictly a function of the Senator tiring of absorbing unanswered attacks, particularly in the form of Merkley’s television spots. Still, Hammond declined to directly address why he didn’t simply wait for the conclusion of the Democratic Senate primary.

“The Senator has pledged for a year that he would wage an aggressive campaign,” Hammond said. “We’re starting to see the first evidence of what the Senator was preparing for.”

In the 5th district, Erickson, a wealthy businessman who ran in 2006, had been the only Republican running until Rep. Darlene Hooley (D) announced that she would retire from the competitively drawn, suburban Portland seat.

Hooley’s announcement motivated Mannix to enter the race, and the former state GOP chairman and two-time gubernatorial candidate set off a round of fireworks last week when he circulated an e-mail from a woman who accused Erickson, who is against abortion, of paying for an ex-girlfriend’s abortion years ago.

Erickson had led Mannix in some early public polling, but the Erickson campaign is now worried that Mannix might have derailed Erickson’s chances of winning today’s primary.

In the past few days, the Mannix campaign dropped a direct-mail hit on the matter, and Mannix’s team claims that its internal tracking polls now have its candidate ahead of Erickson.

Erickson initially denounced the charges. But he subsequently acknowledged in interviews with the local media that the woman in question is his ex-girlfriend. He said he drove her to a doctor and gave her money, but he claimed he didn’t know she would use it for an abortion.

“All of the public and our polling showed us ahead with a widening advantage going into when all of this started,” Erickson campaign spokesman Cary Evans said. “If Mike wins this Tuesday night, then I think voters will have spoken that they don’t believe smears.”

Meanwhile, Democratic operatives were expecting Schrader to defeat Marks, although there was a lack of data to feel comfortable with any prediction.

With the Democratic presidential primary getting most of the attention, Schrader appears better positioned for victory, largely because of his superior name identification — he represents a portion of the 5th district in the Legislature — and the support he has received from stalwart Democratic groups, including labor unions.

“Schrader has a pretty easy victory,” said one Oregon-based Democratic operative. “Schrader has played the favorite most of the time. Marks has always tried to engage him. There’s a sense out there — people think Schrader is going to win.”