Over the past four weeks, during which time he launched a string of attacks on his opponent via television and direct mail ads, Republican John Swallow has managed to gain almost nine points on U.S. Democratic Rep. Jim Matheson, according to a Salt Lake Tribune poll.

The poll, taken Oct. 21 through Oct. 26, shows Matheson still leading Swallow with 44 percent of 400 likely voters saying they would vote for the incumbent.

But Matheson has slipped 11 points and Swallow is closing in with about 39 percent of the vote. A significant number of 2nd District voters - 15 percent - remained undecided.

Challengers in other congressional races also made some gains. But Republican incumbents, U.S. Sen. Bob Bennett and U.S. Reps. Chris Cannon and Rob Bishop, have held onto their wide leads.

The poll has a margin of error of plus or minus 4.9 percentage points for the House races, and 2.8 points for the statewide U.S. Senate race.

Matheson doesn't buy that Swallow's attack ads are working.

"I'm confident I'm going to be ending up well over 50 percent on election night," said the two-term Democrat. "There aren't a lot of secrets in this town. I've just come off a poll and have watched five tracking polls and none of them show your numbers. This one just doesn't seem to make sense."

Bolstering the analysis that Swallow has nabbed Matheson supporters is the near constant number of undecided voters, up just two points from 13 percent on Sept. 26.

But Matheson said he never believed earlier polls showing him leading by 30 points.

"I'm still ahead. Better to be ahead than the reverse," he said.

South Salt Lake police Capt. Beau Babka, the Democratic challenger in Utah's 3rd District, boasts an eight-point jump with 29 percent of the vote, up from 21 percent four weeks ago. He too disputes the numbers.

"It's an inaccurate low for us because of how badly callers mangled my candidate's name," said Babka's campaign spokesman Jeff Bell, who alleges more than two dozen constituents have complained that pollsters mispronounced Babka's first and last names.

Bell is optimistic Babka will prevail, despite Cannon's healthy lead. The four-term congressman has lost five points, but still claims a majority with 53 percent. The number of undecided voters slipped from 19 percent to 14 percent.

Bishop's lead also looks secure. Voters put the 1st District congressman ahead of Democrat Steve Thompson, 56 percent to 24 percent. Both candidates show modest bumps from 54 percent and 21 percent, respectively.

"It's discouraging, but it's reality," said Thompson. "We have at least one more TV debate, maybe we'll pick up some more undecideds and just get her done."

Democratic U.S. Senate candidate Paul Van Dam's campaign looks to be in a holding pattern, moving from 19 percent to 23 percent. Bennett fell one point to 61 percent.