MADISON, Wis. -- A WISC-TV poll of likely voters in Wisconsin conducted early this week shows Barack Obama increasing his lead over John McCain in the race for the White House.

VIDEO: Watch The Report

Among all likely voters, Democratic Sen. Barack Obama leads Republican Sen. John McCain 51 percent to 41 percent.

That's a wider margin than the last WISC-TV poll, released on Sept. 25, which showed Obama leading McCain by six points, 49 percent to 43 percent.

Four percent of voters remain undecided and the margin of error in the WISC-TV poll is plus or minus 4 percent.

The poll was conducted from Oct. 5 through Oct. 6 by Research 2000.

Among men, McCain and Obama are even at 46 percent. McCain previously led by four points.

Among women in the state, Obama has extended his lead -- 56 percent to McCain's 36 percent. Five percent of women remain undecided.

University of Wisconsin-Madison political scientist Charles Franklin said the turning point is the economy and that's reflected in the latest poll numbers.

When survey participants were asked which presidential candidate they trust more to handle the economy, 57 percent said Obama and 31 percent said McCain, with 12 percent not sure.

The poll also determined the favorable opinions for both the presidential and vice-presidential candidates. Obama was 57 percent favorable and Joe Biden was 49 percent. McCain was favorable at 44 percent and Sarah Palin had a favorability rating of 42 percent.

A total of 600 likely voters who vote regularly in state elections were interviewed statewide by telephone for the poll. Those interviewed were selected by the random variation of the last four digits of telephone numbers. Quotas were assigned to reflect the voter registration of distribution by county.

University of Wisconsin-Madison political science professor Charles Franklin said the WISC-TV poll mirrors other recent ones done in the key battleground states.

Franklin said the failing economy is clearly what's helping Obama move ahead and that the longer the crisis last, the longer the polls will favor the Democrat.