When Sen. Jon Kyl, R-Ariz., announced his retirement in 2011, pundits predicted the GOP would easily hold the seat this November. After all, Arizonans last chose a Democrat for Senate in 1988, when as The Wall Street Journal reminisced, "gasoline cost less than 90 cents a gallon … and stirrup pants were in."

Yet Democrat Richard Carmona -- a former Surgeon General and Spanish-speaker of Puerto Rican descent -- is running neck-and-neck with Tea Party Republican Jeff Flake, even though it's Carmona's first high-profile race and Flake is a six-term congressman.

If the Democrats succeed in this improbable coup, and another -- making Arizona a tossup state in the presidential race -- credit will likely be due in large part to a mobilized Latino electorate, with whom Carmona's roots resonate, says Joseph Garcia, head of Arizona State University's Latino Public Policy Center.

The potential for Latinos to alter the nation's political landscape in coming years is broadly recognized, and their impact could be especially significant in Western states with sizeable Latino populations and competitive partisan balances. So far, chronically low turnout rates have made Latino voters a sleeping giant, but their importance is increasingly evident. In 2008, buoyed by excitement over Barack Obama's presidential campaign, Latino turnout helped Democrats take one Arizona congressional seat from Republicans, along with one in Nevada, two in New Mexico, one in Colorado and one in Idaho. In 2010, Latino turnout sagged and Democrats lost nearly all of those seats. Only 38 percent of Arizona's eligible Latinos voted, compared to 52 percent for white voters and 41 percent for blacks, according to Census Bureau surveys.

Arizonans Francisco Heredia and his older brother, Luis, are among the leaders of a West-wide effort to boost these statistics by registering more Latinos -- and making sure they actually cast ballots. "We're out there every day," says Francisco, who runs the Arizona branch of Mi Familia Vota, a nonpartisan group. Dozens of Mi Familia organizers knock on doors, stand outside grocery stores, roam college campuses -- whatever it takes to "grow our political power as a community."

In early October, just before Arizona's voter registration deadline, the group was approaching its goal of registering 7,500 new Latino voters, and had helped 17,000 sign up for mail-in voting -- one method for improving the odds that a voter will follow through. More than 10 other groups are doing similar outreach in Arizona to improve turnout rates.

"This year we'll definitely see the largest number of Latinos voting in the history of Arizona," says Francisco. His brother, the executive director of Arizona's Democratic Party, echoes that prediction. Luis Heredia's team is using "very sophisticated" combinations of polling, market data (who buys what), and analyses of voter addresses and surnames to identify potential Latino voters to organize and target with political messages. He estimates that 389,000 Arizona Latinos were registered in 2008. Now, it's around 589,000 -- a 51 percent increase.

While that's still a small fraction of Arizona's 3.1 million registered voters, the increase seems bound to turn Arizona more blue -- day by day, year by year. The state's Latinos now favor Democratic candidates over Republicans by a 3-1 margin, according to a poll by Seattle-based think tank Latino Decisions, a preference that has increased as Republicans take hard-line stands against undocumented immigrants.

Combining all of those statistics with the most fundamental of all -- the Latino population is growing faster than other ethnic groups, and young Latinos who will reach voting age over the next decade or so are almost all citizens -- and it's obvious, says Garcia: "There's a tsunami coming."

Fred Solop, a Northern Arizona University political science professor, adds: "Whoever can figure out the formula (to get Latino votes) will dominate politics."