Hispanic voters could mean the difference between a victory and a loss for lawmakers in key states where Democrats are fighting for their political lives.
More Latinos today identify with the Democratic Party than a decade ago. In 2008, they voted overwhelmingly for candidate Barack Obama, who earned 67 percent of their votes compared to 31 percent for Sen. John McCain.
They turned out in record numbers in 2008, with more than 85 percent of all Latino registered voters going to the polls, according to the Pew Hispanic Center.
Democrats are hoping for a similar surge this year. In a nationwide survey conducted by Pew Hispanic Center, two-thirds, or 65 percent, of Latino registered voters said they plan to support the Democratic candidate in their local congressional district, while just 22 percent said they would support the Republican candidate.
That support could be crucial for Democrats in states with a large Hispanic population and where candidates are tied in tight political battles such as Arizona, California, Colorado, Florida, Illinois, Nevada and Texas.
The hot-button issue of immigration -- while not necessarily the top issue of concern among registered Hispanic voters -- still has alienated Hispanics from Republicans. From New York to Colorado, GOP candidates have come out forcefully against illegal immigration and amnesty.
"When there are commercials that show nefarious looking actors sneaking around a fence, it doesn't matter how acculturated you are. There is a little bit of a sting out of an ad like that," said Robert E. Lang, professor of sociology and director of Brookings Mountain West at University of Nevada, Las Vegas, referring to Nevada GOP candidate Sharron Angle's campaign ad. "Any time you say, 'This is the other,' and you push the other away from the core, you alienate them in that process."
But that doesn't mean Democrats are spared on that front. There's increased voter discontent about inaction from Democrats on the immigration front, a discontent that some groups have tried to exploit.
Overall, the excitement and momentum that grew in the Hispanic community in 2008 has waned, especially compared to other voting groups. Just one-third of all Latino registered voters say they have given this year's election "quite a lot" of thought, compared to half of all registered voters who say the same, according to Pew.
Compared to other registered voters, Latino voters are likely to be younger and less engaged in the political process, said Mark Lopez, associate director at the Pew Hispanic Center.
Lang said the momentum this year is with older white voters, many of whom relate to the Tea Party and support more conservative policies.
"For now, it [immigration] appears to be a bigger issue with white voters because they're fed up with it. It's an easy pointing finger ... this angst-filled moment for a lot of the white voters," Lang said. "The Democrats have not done an effective job of advertising well. They're vulnerable politically to charges" leveled by Republicans.
There are several House seats for play in Arizona, Texas and Florida where Hispanics could tip the balance, leading both parties to court them extensively.
ABC News took a closer look at those three states, where the battle for the Senate seats has reached new heights.
Perhaps there is no other state where candidates on both sides of the political aisle have historically courted Hispanics as much as in California. Latinos constitute about 21 percent of all registered voters in California, home to more than a quarter of all Hispanic voters in the United States.
Historically, Hispanics have split their support evenly between Republicans and Democrats, but in recent years that has tended to shift toward the latter. Democratic Sen. Dianne Feinstein, who has served in her current position since 1992, received 71 percent of the Latino vote in 2006, according to Pew statistics. In the same year, Republican Arnold Schwarzenegger got 39 percent of the Hispanic vote for his reelection bid as governor, only a slight uptick from 2001.
In 2008, 74 percent of all Latino voters in California voted for Obama and pollsters say they could make a difference for Democratic candidates, if they turn up at the polls.
Despite her targeted efforts, Republican gubernatorial candidate Meg Whitman has lost considerable ground among this important voter group since allegations from her former housekeeper, Nicky Diaz.
Democrat Jerry Brown now enjoys a 29 percentage point advantage over Whitman among the group, 51-22 percent.
In the Senate race, which is considered a toss-up and could come down to the Hispanic vote, GOP candidate Carly Fiorina is attempting to frame the Democrat, Sen. Barbara Boxer, as anti-Hispanic, attacking her on the state's guest-worker program. But the Democratic senator is widely supported by the Latino community. A recent Field Poll found that 48 percent of likely Hispanic voters favored Boxer, 29 percent supported Fiorina and about 25 percent were undecided.
Colorado is home to one of the most neck-and-neck Senate races in the country, another that could be affected by Hispanic turnout.
Republican and Tea Party-favored Ken Buck and third party candidate Tom Tancredo have turned off many Hispanics with hardline stances on immigration, analysts say. At the same time, views toward incumbent Sen. Michael Bennet are also mixed.
The Hispanic share of the voter base has increased steadily. In 2008, 13 percent of voters were Hispanic, compared to just 8 percent in 2004. Latinos, as in many other states, voted for Obama in 2008 -- by 61-38 percent.
The Hispanic vote is decidedly in Bennet's favor. But it remains to be seen whether the minority group goes to the polls with the same enthusiasm as in 2008.
Democrats aggressively have courted Hispanic voters through the years. In 2008, they sponsored a soccer team called "Los Democratas." They have hired Spanish speakers to take part in grassroots campaigns and supported labor unions dominated by Hispanics, like the Nevada culinary union.
It was one of the states where candidate Obama campaigned aggressively and ended up winning 76 percent of the Hispanic vote, the highest in the country.
While Senate majority leader Harry Reid's outreach into the Hispanic community is not as high as it was in 2008, it is still more extensive than the outreach by his Republican challenger Sharron Angle.
Hispanics comprise 14 percent of all eligible voters in Nevada this year and could tip the balance in favor of the embattled majority leader.
"The Latino vote is going to be critical in this race," said John Tuman, chairman of the political science department and director of the Latin American studies program at the University of Nevada, Las Vegas. "This is a critical demographic for Reid and his campaign. And the Democratic Party, in general, in Nevada has a real, sustained outreach effort for the Latino community."
Angle, meanwhile, has taken a lot of heat from Latino voters for featuring men crossing the fence in her campaign ads. When Hispanic students questioned her recently about why the men were brown-skinned, Angle said she was "not sure that those are Latinos in that commercial."
Her reasoning: "I don't know that all of you are Latino. Some of you look a little more Asian to me," Angle told students, a comment that didn't go down well with Hispanics.
ABC News' Maya Srikrishnan contributed to this report.