Advertising is having a huge effect in the Senate race.

With Democratic candidate Kay Hagan on the air during the May primary, her numbers improved against U.S. Sen. Elizabeth Dole.

Dole then got a bump from her own ads, but another round of ads attacking Dole has narrowed the gap again. The entrance of Libertarian Chris Cole to the race also complicated things.

Here are the numbers:

May 8-9: Dole 48, Hagan 43
May 14-17: Dole 45, Hagan 43
May 17-19: Dole 50, Hagan 46 
May 28-29: Dole 47, Hagan 39
June 10: Dole 53, Hagan 39
June 18: Dole 48, Hagan 38
June 26-29: Dole 51, Hagan 37
July 12-14: Dole 54, Hagan 42
July 15: Dole 54, Hagan 43
July 14-16: Dole 47, Hagan 38, Cole 2
July 23-27: Dole 49, Hagan 40, Cole 4
July 28-30: Dole 50, Hagan 42
Aug. 9-11: Dole 46, Hagan 41, Cole 7

In all of the polls, Dole is ahead, but her lead ranges from as high as 14 points in June to as low as two points in mid May. The recent tightening shows this could be a volatile race. 

The gap in the Senate race is closing.

According to a recent poll by SurveyUSA for WTVD in Raleigh, U.S. Sen. Elizabeth Dole had 46 percent, Democratic opponent Kay Hagan had 41 percent and Libertarian Chris Cole had seven percent. Five percent were undecided.

The poll shows Dole down after several ads by third-party groups attacking her have aired on North Carolina radio and television.

The pollsters caution that Cole's support may be overstated.

"Support for 3rd-Party candidates often collapses as Election Day nears, and that may or may not happen in North Carolina in 2008," they write. "Today, 12 weeks out, voters with a message they want to deliver to both Republicans and Democrats are using Cole as their protest vehicle." 

The survey of 655 likely voters was taken Aug. 9-11 and has a margin of error of plus or minus 3.9 percentage points.

U.S. Sen. Elizabeth Dole's lead narrowed slightly.

According to a recent survey by Democratic firm Public Policy Polling, the Salisbury Republican got 49 percent, Democratic rival Kay Hagan got 40 percent and Libertarian Chris Cole four percent.

Seven percent were undecided.

Though Dole is ahead, she's lost a little ground compared to other recent polls, a change attributed by pollsters to advertising.

"Elizabeth Dole got a bump when she went on the air in late May, but that has largely dissipated," said firm owner Dean Debnam in a statement. "With the news in the last week that the DSCC plans to make a considerable expenditure on Hagan’s behalf, this race could end up being closer than previously anticipated."

The automated survey of 823 likely voters was taken July 23-27. It has a margin of error of plus or minus 3.4 percentage points. 

U.S. Sen. Elizabeth Dole retains her lead.

According to a recent survey by the conservative Civitas Institute, the Salisbury Republican had 47 percent support, Democratic rival Kay Hagan had 38 percent and Libertarian Chris Cole had 2 percent. Fourteen percent were undecided.

"Dole continues to hold onto a very strong lead even as Hagan has matched her dollar for dollar over the last few months in fundraising," said executive director Francis DeLuca.

That matches recent polls by Rasmussen Reports, Survey USA and the Democratic firm Public Policy Polling, which all show Dole with a substantial lead.

The live-caller survey of 600 likely voters was conducted July 14-16 by TelOpinion Research of Alexandria, Va., The margin of error is plus or minus 4.2 percentage points.

U.S. Sen. Elizabeth Dole retains a comfortable lead.

In a recent survey by Public Policy Polling, the Salisbury Republican had 51 percent support, while Democratic challenger Kay Hagan had 37 percent. Twelve percent were undecided.

The double-digit lead matches recent polls by the conservative Civitas Institute and Rasmussen Reports, which showed Dole rebounding after a Hagan boost during the primary. No poll has included the recently announced Libertarian candidate.

Pollster Tom Jensen writes that Dole was helped by a June ad campaign and Hagan's struggle to connect with independent and black voters.

"Elizabeth Dole has rebounded strongly after Kay Hagan's post-primary bounce in the polls," he writes.

The automated survey of 1,048 likely voters was done June 26-29. It has a margin of error of plus or minus three percentage points. 

The N.C. Libertarian Party will have 38 candidates on the fall ballot.

The newly re-recognized party formally presented its list of candidates for state and federal offices to the State Board of Elections Monday.

As previously announced, Duke University professor Mike Munger will run for governor. Phillip Rhodes of Chapel Hill is running for lieutenant governor and Mark McMains of Fuquay-Varina for commissioner of insurance. Twenty-four candidates are running for legislative seats.

Chris Cole, a contract postal worker who lives in Huntersville, is running for U.S. Senate. Five candidates are running for Congressional seats: Will Adkins of Cary, Maximillian Longley of Durham, Thomas Hill of Concord, Andy Grum of Matthews and Keith Smith of Bostic.

Libertarian presidential candidate Bob Barr will also be on the ballot. 

U.S. Sen. Elizabeth Dole has a 10-point lead.

In a recent survey for the conservative Civitas Institute, Dole had 48 percent, while state Sen. Kay Hagan had 38 percent. Libertarian candidate Chris Cole had one percent and 13 percent were undecided.

"Senator Dole has been able to open up a significant lead over her challenger due to the effective advertising campaign she has run over the past month," said executive director Francis DeLuca. "Since last month, Senator Hagan concluded her advertising in conjunction with the end of her primary race, while Senator Dole has just begun to reintroduce herself to voters."

In last month's poll for the group, Dole led Hagan by just two points. Other recent polls have shown Dole opening a wider lead against Hagan since advertising on television.

The live-operator poll of 600 likely general election voters was conducted June 11-13 by TelOpinion Research of Alexandria, Va. The margin of error is plus or minus 4 percentage points.