President Bush's young, Hispanic nephew and his bride are on the campaign trail — in Mexico, where they are joining the increasingly vigorous battle for the votes of 1 million U.S. citizens living south of the border.

George Prescott Bush (search) — whose father is Florida Gov. Jeb Bush (search) and mother, Columba, is originally from Mexico — was arriving late Friday for a four-day tour in support of his uncle's re-election campaign. The trip was paid for by the political nonprofit Republicans Abroad (search).

The campaign for Democratic presidential nominee John Kerry also is courting American voters in Mexico — and relying on family to deliver the message. Diana Kerry, chairman of Americans Overseas for Kerry, came to Mexico City in July to stump for her brother.

Organizers of George P. Bush's visit are emphasizing the Bush family ties to the country, believed to be home to the largest population of U.S. citizens living abroad.

Republican and Democratic campaign officials estimate about 1 million Americans and dual U.S. citizens live in Mexico, although it's unclear how many may vote this year.

"He wants to speak — obviously — to the Americans, with some friends of his, and also wants to show his wife the country of his mother," said Larry Rubin, president of the newly formed Republicans Abroad chapter in Mexico.

Married this month to Amanda Williams, George P. Bush is the grandson of migrant worker Jose Maria Garnica, who separated from his wife and still lives in Mexico. It's unlikely Bush and his wife will visit Garnica, although they will be traveling to Guanajuato state, where Garnica lives, Rubin said.

"There will be other visits. It's not his first or his last time here," Rubin said.

Both Republicans and Democrats report an increased interest in absentee voting in Mexico.

"It just seems like it's a little more important than we realized," Cherokee Randolph said while waiting in line Thursday outside the U.S. Embassy to request an absentee ballot. The 43-year-old musician didn't vote in the 2000 presidential elections, but she plans to cast a ballot for Kerry this year.

"There's a little escapism when you're living abroad," she said. "We still have the responsibility to cast our vote."

President Bush's victory in Florida was decided by a margin of 537 votes in 2000, after thousands of votes were counted from Floridians abroad.

Given predictions of another close contest in November, campaigning and overseas registration drives are just common sense for both parties, said Harvard professor Gary King, a co-compiler of a survey analyzing Florida's overseas vote in 2000.

Several million Americans live abroad, though they are less likely to vote than people living in the United States. King noted that voting overseas is more difficult logistically.

That hasn't stopped Republican and Democratic organizers from trying to get out the vote this year in Mexico, with both parties launching registration drives.

Republicans Abroad is pumping money into Mexico, purchasing political advertisements in English-language media across the country, according to Ryan King, deputy director of the Washington-based group.

George P. Bush plans to meet with business leaders in Mexico City and later travel to large American communities in and around Guadalajara and San Miguel de Allende.

Meanwhile, Kerry supporters leapfrogged ahead to hold a voter-registration and ballot-request drive in Guadalajara on Thursday.