The Conservatives have hit their lowest level of support since the last federal election, a poll suggests, leaving them statistically tied with the Liberals and just a few points ahead of the Official Opposition.

The Nanos Research survey, which was conducted in February, puts the Conservatives at 31.5 per cent support at the national level, down from 34.3 per cent in January. In contrast, 29.1 per cent of respondents said they supported the Liberals in the February poll, placing the party in a virtual tie with the Conservatives. The NDP was slightly behind both parties with 27.2 per cent of support.

The latest numbers highlight a gradual softening in support for the Conservatives that began nearly two years ago, according to data collected by Nanos Research.

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"Polls are snapshots in time, but it's the trend that counts," pollster Nik Nanos said. "And when you look at the trend line for the Conservatives, over the last two years, it's basically negative coming out of the election."

After fulfilling a series of promises, such as cutting the GST and signing trade deals, the Conservatives could be running out of big-ticket policy ideas, Mr. Nanos suggested. "Since the last federal election, there aren't any significant marquee public policy issues that the Conservatives have put in the window."

At the same time, both the Liberals and the NDP have avoided big political gaffes in recent months, he said, leaving fewer openings where the governing party can take advantage.

The poll was released as Liberal leadership hopefuls enter the last few weeks of the campaign for their party's top position. Support could flip back and forth between the NDP and the Liberals as that race comes to a close in April, Mr. Nanos said.

In Quebec, the Bloc Québecois showed a slight improvement between January and February and is now in a statistical tie with the Liberals, according to the poll. But both parties remain well behind the dominant NDP in that province.

In Ontario, the Liberals and Conservatives are in a dead heat, the poll suggests, while all three major parties are virtually tied in British Columbia. Both provinces are key federal election battlegrounds.

After the poll was completed, a simmering controversy over senators' expense claims became more heated, casting an unwelcome light on the Red Chamber that could prove damaging to the governing Conservatives. Many of the senators caught up in allegations that they may have improperly claimed taxpayer money were appointed by Prime Minister Stephen Harper.

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The opposition NDP, which has no senators and favours abolishing the chamber altogether, has used the controversy to criticize the Conservatives.

The random telephone survey of 1,000 adult Canadians was conducted between Feb. 19 and 24. The responses of 717 people who said they are committed voters are considered to accurately reflect the views of the Canadian public within 3.7 percentage points, 19 times out of 20.