LANSING, Mich. (AP) — A flurry of recent visits to Michigan by Democratic presidential candidate Barack Obama likely helped the Illinois senator take a slight lead over Republican John McCain in a new poll released Thursday.

Forty-eight percent of 1,411 likely Michigan voters polled by Quinnipiac University said they'd back Obama if the election were held today, while 42 percent backed McCain. Obama was leading 46 percent to 38 percent among independents.

Quinnipiac conducted simultaneous polls between June 17 and Tuesday in Michigan, Colorado, Minnesota and Wisconsin — all considered key battleground states. Obama was leading in all four.

McCain's strong showing among white voters in Michigan and Colorado helped him keep Obama to a smaller lead than in Minnesota and Wisconsin, where Obama led by margins of 17 points and 13 points, respectively.

But the 48 percent to 42 percent edge McCain holds among white voters in Michigan may not be enough, said Peter Brown, assistant director of the university's Polling Institute in Hamden, Conn.

"Michigan is a blue-collar state with a large white, working-class vote, the kind of voters with whom Senator Obama had problems during the primaries," Brown said in a release. "But at this point, Senator McCain isn't doing nearly as well among that group as he needs in order to carry Michigan."

Black residents make up 14 percent of the state's population, and Obama leads McCain among black voters 89 percent to 6 percent. He also leads among union households of all races, 57 percent to 32 percent.

Leah Yoon, regional spokeswoman for the McCain campaign, said Thursday that a recent spate of campaign visits by Obama undoubtedly helped the Illinois senator in the poll.

Obama made a two-day swing through Michigan last week with stops in Flint, Detroit and Taylor. Earlier in the month, he was heard by 2,000 people at Troy High School and stopped by a distribution center in Oakland County's Waterford Township. On May 14, he visited a stamping plant in Sterling Heights, held a town hall meeting in Warren and appeared at a Grand Rapids rally with former rival John Edwards.

In contrast, McCain's last campaign stop in Michigan was a May 7 town hall meeting at Oakland University in Rochester. But the senator hasn't ignored Michigan, pouring hundreds of thousands of dollars into the state for a variety of campaign ads in recent weeks. Obama didn't begin running ads in the state until last Friday.

McCain plans to campaign in Michigan on July 10 and 17, according to GOP activist Chuck Yob, who's helping with McCain's Michigan campaign.

Yoon said she's confident McCain's message will win over Michigan voters.

"If anyone didn't think Michigan was going to be an uphill battle for John McCain, they're wrong," Yoon said. "(But) we're going to continue to be encouraged that this state is within striking distance."

The Arizona senator has a base to build on, having won Michigan's 2000 GOP primary and finishing second behind favorite son Mitt Romney in this year's GOP race. McCain was ahead of Obama, 44 percent to 40 percent, in a mid-May EPIC-MRA poll conducted for The Detroit News and TV stations WXYZ, WILX, WOOD and WJRT.

Obama national campaign manager David Plouffe told reporters in a conference call that he's happy with how Obama is doing in the Upper Midwest, including Michigan, a state where Obama had taken his name off the Jan. 15 primary ballot.

"We have a lot of work to do there," Plouffe said of Michigan. "But given the fact that we didn't campaign there, that John McCain has run in Michigan hard in 2000 and 2008, to start from this position we think is important."

Fifty-four percent of Michigan voters have a favorable opinion of Obama, compared with 27 percent unfavorable opinion. For McCain, 49 percent have a favorable opinion, while 29 percent have an unfavorable opinion.

The Michigan poll has a margin of sampling error of plus or minus 2.6 percentage points. It was commissioned by the Wall Street Journal and washingtonpost.com.

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EDITOR's NOTE: Kathy Barks Hoffman heads the Lansing AP bureau and has covered Michigan politics since 1986.