Hamilton Mountain NDP MP Chris Charlton is calling an on-line election advertisement mocking her constituency office's hours "a sign of desperation" from her Liberal opponent.

But rival Tyler Banham maintains he's struck a nerve, both with voters and Ms. Charlton.

The Internet ad, which features a telephone ringing at 3 p.m., is a spoof of an attack ad by Hilary Clinton during her unsuccessful bid for the U.S. Democratic presidential nomination.

In the Clinton ad, the phone was ringing at 3 a.m. and used to imply that her challenger, Barack Obama, lacked the necessary experience to be president.

In Mr. Banham's version, no one answers the phone and a recorded message from Ms. Charlton states that her constituency office's hours are 8:30 a.m. to 1 p.m., Monday to Friday. The caller is invited to leave a message after the beep, but the line is disconnected, leaving a dial tone.

Ms. Charlton said the ad is backfiring because people who deal with her office know it misrepresents the situation.

She said her staff uses the afternoon to work on case loads, visit constituents and "do outreach," like clinics to help people claim disability tax credits.

"I think that's all part of being an effective member of Parliament," Ms. Charlton said.

"People who come to our community office know better, and so they're shaking their heads," she said.

"For people who are sort of watching the campaign from the sidelines, they're not appreciating the negative campaign attacks."

But Mr. Banham said the advertisement is getting positive feedback at the door.

He said it was created a year ago from an unedited message recording and his research has confirmed that Ms. Charlton is the only MP in Canada with such limited office hours.

"Three hundred and seven other members of Parliament can have their office open until five o'clock," Mr. Banham said.

"We've heard this at the door. People are angry about that," he said, claiming frustrated constituents often turn to Hamilton Centre NDP MP David Christopherson's office for help instead.

"They vote for me, they get the working-family constituent hours, that we're open until seven o'clock twice a week, five o'clock the other three days, and we take weekend appointments."

An assistant did answer the phone when a reporter called Ms. Charlton's office shortly after 3 p.m. last Thursday -- after the ad campaign was launched and received media coverage.

Mr. Banham sees that as a sign the ad is working.

"I think the very fact that she's picking up her phone after one o'clock shows that we're already making change with her campaign," he said.

But Ms. Charlton denied any such connection. Her office is staffed until 4:30 p.m., she said, "and if someone knocks on the door, we never turn anybody away."

"The cases that come to our office, they need investigation, they need advocacy, and staff in my office need to have that time to do the follow-up," she said. "Otherwise, you're a meet-and-greet office, but you never get anything done."

Conservative candidate Terry Anderson said he favours a more traditional approach.

"You have to be accessible to people and office hours are something you have to work around your constituents," he said.

"It's not my place to tell Chris Charlton how to run her office, but I personally believe that nine to five at a minimum are the hours that I would open my office. But she has to make her own decisions and people can make their own choices."