Aug. 23 (Bloomberg) -- Barack Obama and John McCain will target appeals at vital groups of voters during their parties' nominating conventions over the next two weeks.

A new Bloomberg/Los Angeles Times poll shows that Obama, the Democratic candidate, is trailing McCain among several groups that Democrats usually need to carry if they want to win a presidential election.

McCain, a Republican senator from Arizona, is beating Obama by 8 percentage points among Catholics and has a 50-36 percent advantage among voters 65 and older. For all of Obama's efforts to reach out to churchgoers, the Illinois senator trails McCain by a bigger than 3-1 margin among white evangelicals.

McCain has his own challenges. Independent voters favored Obama 46-35 percent in the Aug. 15-18 survey, a reversal from two months ago. The Republican isn't matching Obama's appeal with younger voters. Obama leads 49-40 percent among voters under 45 years old.

Not surprisingly, McCain has a 2-point advantage in households that make more than $60,000 a year, while Obama has a comfortable 10-point lead in homes with less than $40,000 of annual income.

A vital constituency for both candidates is middle-aged women, among whom Obama and McCain are deadlocked right now.

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Obama and McCain may only get a blip of increased support in public opinion polls after their conventions instead of the late-summer bounce campaigns typically expect.

This year, conventions are scheduled for consecutive weeks, with Republicans assembling Sept. 1 in St. Paul, Minnesota, almost before Democrats can clean up the confetti in Denver.

With no time to build momentum from his week of televised hoopla, Obama may have to settle for a modest uptick in the polls, says Michael Dimock, associate director at the Pew Research Center in Washington.

``It's hard for the Democrats to get the long-term impact they would like, given the Republican convention will be coming right after,'' he says. What's more, Republicans probably will steal some of Obama's thunder by naming McCain's running mate the day after Democrats adjourn.

Obama's fighting for attention by making next Thursday's acceptance speech at 76,000-seat Invesco Field at Mile High.

Republicans may have trouble of their own matching ``a Democratic convention that has a lot of drama to it,'' Dimock says.

McCain's acceptance speech is set for Sept. 4, the same night as the National Football League's first regular-season game, a televised prime-time matchup between the defending Super Bowl champion New York Giants and the Washington Redskins.

Post-convention bounces have already been shrinking with the growth of 24/7 news. Four years ago, President George W. Bush and his Democratic opponent, Massachusetts Senator John Kerry, gained almost no ground, according to a study by the American Enterprise Institute.

Karlyn Bowman, who tracks polling for Washington-based AEI, says modest bounces typically don't last very long anyway.

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Republicans aren't wasting time in trying to steal Obama's spotlight: McCain is scheduled to appear on NBC's ``Tonight Show with Jay Leno'' on Monday, the first day of the Democratic pageant.

McCain, who turns 72 on Aug. 29 and would be the oldest person elected to a first presidential term, is sharing Leno's stage with Dara Torres, the 41-year-old silver medal-winning swimmer who prevailed in the Beijing Olympics over women half her age.

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Forty years after bloody clashes between protesters and police at the 1968 Democratic convention in Chicago, a coalition of activists calling itself Recreate68 plans marches, concerts, and street theater in Denver.

A highlight: Protesters will try to use their combined psychic energy to levitate downtown Denver's U.S. Mint and ``shake the money out.'' They also plan an ``Everything for Everyone: Anti-Capitalist March'' and a ``Fundraiser Disruption,'' according to the group's Web site.

Mark Silverstein, legal director of the ACLU of Colorado, says the Recreate68 name is meant to capture 1968's ``spirit of grassroots movements for social change,'' and not to evoke violence that marred the Chicago convention.

Still, authorities say they are prepared for the possibility of mass arrests, converting an empty warehouse into a holding facility.

Police have restricted parades and demonstrations to specific areas, and a federal court upheld the limits.

``I don't think James Madison meant freedom of speech meant you can come and yell in someone's face,'' says Denver Mayor John Hickenlooper, a Democrat.

The rules ``depict protesters as these scary people who are going to do terrible things,'' says Zoe Wood, an organizer for the antiwar group CodePink. ``That is really not true.''

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Ronald Reagan loved jellybeans and Bill Clinton thirsted for Diet Coke. Obama says he's nuts for peanuts.

``I'm a peanut fanatic,'' Obama said this week when his campaign stopped at a roadside shop in Emporia, Virginia. ``I eat them all day long.'' Obama used a credit card and bought the smaller of two bags of peanuts on display, saying he didn't want to look like a ``pig.''

While Obama's enthusiasm may appeal to voters in peanut- growing states like Virginia, Georgia, and Florida, he's frequently seen enjoying pistachios, which are a staple on his campaign airplane.

To contact the reporter on this story: Bob Drummond in Washington at bdrummond@bloomberg.net; Catherine Dodge in Washington at cdodge1@bloomberg.net.

Last Updated: August 22, 2008 18:35 EDT