* Neither of main parties could win election now: poll

* Opposition leader Ignatieff has poor personal ratings

OTTAWA, May 18 (Reuters) - Canada’s ruling Conservatives are still slightly ahead of the main opposition Liberal Party, but do not have enough support to win an election now, according to a poll released on Tuesday.

The Harris-Decima survey for the Canadian Press put the Conservatives at 32 percent popular support -- up three points from a poll by the same firm three weeks ago -- while the Liberals were up one point at 28 percent. The left-leaning New Democrats were down three points at 17 percent.

The Conservatives and Liberals have been locked together for much of the year, with neither party attracting enough support to win even a stable minority government.

The Conservatives, who have been in power since early 2006, won a strengthened minority in October 2008.

Their support has remained largely stable, despite a series of controversies. Harris-Decima pollster Allan Gregg said one reason could be the lackluster performance of Liberal leader Michael Ignatieff, who has largely struggled since taking over the party in December 2008.

The survey said 26 percent of Canadians had a positive impression of Ignatieff while a full 52 percent had a negative impression. Prime Minister Stephen Harper was viewed unfavorably by 51 percent while 42 percent approved.

“Opposition leaders usually do not evoke strong negative feelings, so it’s very unusual,” said Gregg. The Conservatives portray Ignatieff -- a former academic and broadcaster -- as a snob who is out of touch with ordinary voters.

The Harris-Decima survey of 2,007 adults was conducted from May 6 to 16 and is considered accurate to within 2.2 percentage points, 19 times in 20. (Reporting by David Ljunggren; editing by Rob Wilson)