As John McCain returned from his visit to Latin America, Barack Obama ventured into what might seem like foreign territory.

The presumptive Democratic presidential nominee is spending his Fourth of July weekend in several Republican states, as polls show him taking some surprising leads over his GOP rival.

He and his family attended an Independence Day parade Friday in Butte, Mont., and were hosting a "family picnic" later in the day.

Only two Democratic presidential candidates have carried the state in the general election since 1948. But Montana was the site of Obama's final victory in the Democratic primary. It is just the kind of overlooked state that helped him build his delegate lead against Hillary Clinton and is one of several untraditional states the Illinois senator wants to put in play this November.

"I'm a firm believer that 90 percent of success is showing up," Obama said Thursday in North Dakota, another red state. "And Democrats haven't been showing up in these places and talking to people."

His campaign promises "significant" investment in Montana and already has been spending a sizable amount of time and money there, hiring a state director and staff while running TV ads detailing his background and qualifications.

One new poll shows he actually has taken the lead in Montana.

A Rasmussen Reports survey out Thursday showed Obama leading John McCain 48-to-43 percent. That's the reverse from a similar Rasmussen poll in April.

"I think there's the possibility of significant realignment, politically, in this election," Obama said Thursday.

Obama also has taken the lead in Colorado, another typically Republican state. He visited Colorado Springs Wednesday during his weeklong tour discussing "American Values."

Obama plans to campaign in the battleground of Missouri on Saturday. And he plans to visit North Carolina, Georgia, Ohio and Virginia next week.

In Montana, Republicans hold the historical advantage, but McCain has no staff there and has yet to visit this election year.

The McCain campaign remains confident.

"The more often Barack Obama travels to Montana, the more voters will be reminded of why they disagree with him on the issues they care about most," McCain spokesman Tom Steward said.

As Obama tries to expand his base, McCain is trying to expand his -- reaching out to former Hillary Clinton supporters and independent voters and making a play for the Hispanic vote.

The Arizona senator launched a Spanish radio ad Thursday, as he was about to return from a three-day trip to Colombia and Mexico. In the ad, a Latino McCain supporter says McCain has "earned the trust of Latinos" and that "it seems to me that the other candidate has just discovered the importance of the Hispanic vote."

FOX News' Bonney Kapp and The Associated Press contributed to this report.