PORTLAND — As local election officials began to mail out a record number of ballots to Oregonians Friday, officially kicking off the state’s 18-day election process, Republican Sen. Gordon Smith and Democratic rival Jeff Merkley sparred over a slew of recent advertisements.

The ads were the latest flash point in what is a close and heated race between the two men.

For the first time this election cycle, the Democratic Senatorial Campaign Committee seized on allegations raised in several Willamette Week articles that Smith’s frozen-food business employs illegal immigrants.

Matthew Miller, a spokesman for the Senatorial Campaign, said the allegations reinforced the fact that Smith, who has called for immigration reform, is a hypocrite. “The issue of Gordon Smith saying one thing and doing another is something that’s been a theme of this campaign,” he said.

Smith has repeatedly denied any wrongdoing by his company, Smith Frozen Foods, which he owns with his wife. “I’m proud of my company,” he said during a debate held in Portland last week. “All of our workers are documented.”

Lindsay Gilbride, a spokeswoman for the senator, called the ads “a new low” for the Democratic campaign.

“The ad is solely based on ridiculous allegations from a liberal tabloid,” she said. “The ad has no basis in fact. It’s a smear campaign.”

The fire over campaign advertisements went both ways Friday.

Minutes before Merkley appeared in a single-chair debate hosted by the City Club of Portland, a representative for Democratic Sen. Ron Wyden assailed Smith for featuring Wyden in a recent advertisement.

Smith’s campaign has released a number of ads touting bipartisan work with Democrats such as presidential candidate Barack Obama, Wyden and Massachusetts Sens. Edward Kennedy and John Kerry.

A recent ad includes footage of Wyden saying that Smith, “my friend, my partner, always meets me halfway.”

It ends with a picture of Smith and Wyden side by side. Smith signs off saying, “I’m Gordon Smith, and I approve working together across party lines. And this ad.”

Wyden’s chief of staff, Josh Kardon, called Smith’s ad confusing and deceitful. Though Wyden considers Smith a friend, Kardon said, Wyden has many friends whom he does not support for elected office. Kardon said Wyden’s words were taken from a nonpartisan event, and he called for them to be removed from the partisan TV spot.

Kardon said that Wyden has received dozens of phone calls from confused and angry voters wanting to know why Wyden “made a commercial” for Smith.

“At the end of the day, all a man or a woman has is their good name,” Kardon said. “The ads are intentionally confusing to voters.”

Wyden recently asked Smith to remove his signature from another commercial. Smith did.

But this time, Smith’s campaign is holding firm. Gilbride dismissed allegations that the advertisement is confusing.

“Oregonians know the Smith-Wyden partnership,” she said. “This ad accurately reflects their relationship, and it will remain on the air.”

Rep. Earl Blumenauer, D-Ore., spoke on behalf of Obama. Though the campaign has not specifically asked that any advertisements come down, Blumenauer did stress that the presidential candidate and Oregon front-runner is backing Merkley.

“It’s important that there is no confusion,” he said.

Through his staff, Kennedy issued a statement Friday in support of Merkley.

Meanwhile, the Oregon secretary of state’s office continued to tally the number of registered voters. At last count, 2,164,333 Oregonians were registered to cast a ballot. That’s about 20,000 more than were registered during the 2004 election and the office is still counting.

Democrats continue to outnumber Republican by a significant margin — about 935,000 to 697,000.

That’s in large part because of massive registration drives by the Obama and state legislative campaigns.

“We have worked very hard here in the state of Oregon,” said Sahar Wali, a spokeswoman for Obama’s Oregon campaign. “We’ve literally got thousands of volunteers who have been knocking on doors, making phone calls,” she said.

Still, the campaign isn’t taking the registration lead to the bank just yet. “In order for those registrations to mean something, we’ve got to get people out to vote,” she said.