Several Republican victories, including the reelection of Florida Gov. Rick Scott, suggest Democrats are having trouble energizing the multiethnic coalition that has supported President Obama. (Scott McIntyre/AP)

The Republican rout Tuesday helped the GOP regain ground among Hispanic voters, a bloc that both parties consider crucial for the 2016 presidential race but that not long ago seemed an increasingly stalwart Democratic constituency.

In Florida and Colorado, two states likely to be major battlegrounds for the White House, GOP candidates won competitive races for governor and Senate, respectively, after aggressive outreach campaigns that included Spanish-language ads.

In Texas, Gov.-elect Greg Abbott won 44 percent of the state’s Hispanic vote, according to exit polls, while even in Georgia, surveys showed that more than 4 in 10 members of the state’s small Hispanic electorate backed the party’s Senate candidate.

The results underscore the extent to which Democrats struggled Tuesday to mobilize the multiethnic coalition that powered Barack Obama’s victories, with turnout among African Americans and young people also proving insufficient to help Democrats overcome Republican advantages with white and older voters in key contests.

They foreshadow a challenge confronting Democrats over the next two years as they build a strategy to motivate core voters who have been inspired by Obama but have shown less interest in turning out for other candidates.

During a news conference after election night, President Obama says he will continue to act through executive authority on immigration reform, as Congress has continuously delayed the issue. (AP)

“It’s not a massive phenomenon, but Latinos identified less with the Democratic Party and a growing share identified with Republicans,” said Mark Hugo Lopez, director of Hispanic Research at the Pew Research Center. He said the results suggest that, with the right candidate, Republicans could shave Democrats’ advantage with Hispanics and put states that Obama won back into play.

Nationally, the polls showed that Hispanic voters favored Democrats over Republicans by 28 percentage points, a significant margin but still a drop from 2012, when they preferred Democrats over Republicans by 38 percentage points, though a bit wider than the Democratic advantage in 2010.

Meanwhile, Hispanics made up 8 percent of the overall electorate Tuesday. That number is down from 10 percent in 2012 and flat since 2010, a striking figure given the nation’s quickly expanding Hispanic population.

The results came two years after Obama’s 71 percent share of the Hispanic vote was widely seen as a sign that the country’s changing demographics were likely to create strong and durable advantages for Democrats. Some GOP leaders feared that Republican opposition to a proposed immigration overhaul that would have legalized millions of undocumented immigrants would further hurt their cause.

But Democrats may have failed to capi­tal­ize on that apparent advantage. Immigrant advocates were at first deeply disappointed with what they perceived as a lackluster White House effort to press for an immigration bill. They grew more disenchanted when Obama delayed a highly anticipated executive order to halt many deportations.

Partisan jockeying on the issue resumed Wednesday. Obama said in his post-election news conference that by the end of the year, he plans to do everything he can “lawfully through executive actions to improve the functioning of the existing system.” Sen. Mitch McConnell (R-Ky.), in line to become Senate majority leader, said unilateral action by Obama would be “a mistake.”

Tuesday’s results were especially notable in Texas, a conservative state that Democrats have maintained could shift left in coming years because of its dramatically growing Latino population.

But exit polling showed Abbott significantly improved Republican performance among Hispanic voters over Gov. Rick Perry (R), who has boasted that he captured 40­ percent of the Hispanic vote. Abbott defeated state Sen. Wendy Davis by 20 points.

Abbott’s strong performance came in the face of a concerted Democratic effort to use social media and advanced voter-targeting techniques to boost minority voting through a political action committee called Battleground Texas. Founded by Obama veteran Jeremy Bird, the group is dedicated to turning Texas into a durable swing state.

Abbott’s campaign said his efforts included 17 visits to the Rio Grande Valley along the Mexican border, including the Friday before Election Day. The campaign stationed 14 field staffers in south Texas, including four devoted to the Valley, more than any previous Republican. And Abbott spent more than $3 million to air thousands of radio and television ads in Spanish.

Ross Hunt, a consultant for Abbott’s campaign, said the results showed Democratic claims that demographics are destined to turn the state blue are “complete nonsense.”

“They failed to move the needle at all,” he said.

Bird, in a post-election memo, said Battleground Texas organizers always knew that their effort would “take time and commitment.”

In Colorado, where Latinos make up 21 percent of state residents, Republicans hosted Spanish-language phone banks featuring the state’s party chairman, who learned the language as a missionary in Southern California. Their efforts were boosted by three full-time Hispanic outreach coordinators employed by the Republican National Committee, which had sent workers to 11 states with significant Latino populations.

Exit polls provided little data about Latino voting in the key state, but Rep. Cory Gardner’s comparatively comfortable four-point win over incumbent Sen. Mark Udall (D) suggests the GOP effort to blunt the Democratic advantage had some impact.

In the Florida governor’s race, Hispanics supported former governor Charlie Crist (D) over incumbent Gov. Rick Scott by 20 points, similar to the margin by which they backed Obama over Mitt Romney two years ago. But the Hispanic share of the electorate dipped from 17 percent two years ago to 13 percent — illustrating the difficulty for Democrats in building the same level of excitement in their base for a midterm election as they can for a presidential contest.

The Crist campaign sought to re-create the Obama coalition that won Florida in 2008 and 2012, relying on many of the same strategists who worked for Obama in those years. Crist’s team also designed his campaign to mimic aspects of the Obama campaigns, opening field offices and hiring grass-roots organizers to develop the same voter-targeting techniques. Yet, in the end, Crist advisers said, the coalition simply did not turn out in the numbers that were needed to win.

“We had a very substantial ground operation,” said Dan Gelber, a top Crist adviser. “It’s just they ultimately plowed so much money at the end that we hit a wall. It was too much money and not enough enthusiasm [among core Democrats].”

Attention in Georgia had been largely focused on whether Democrats could rack up enough votes among the state’s significant black population, even without Obama on the ballot, to help Democratic Senate candidate Michelle Nunn force a runoff with Republican David Perdue.

In the end, black voters made up 29 percent of the electorate and backed Democrats over Republicans by 85 percentage points, numbers that matched what Democrats had thought they would need. But Perdue still beat Nunn by eight percentage points and exceeded the 50 percent mark needed to avoid a runoff, as he exceeded expectations with white voters and the state’s small Hispanic voting population.

Simon Rosenberg, executive director of NDN, a pro-Democratic think tank that has studied the changing electorate, said Tuesday’s results did not reflect a structural shift in the Hispanic vote. But he said the numbers contained warning signs for Democrats, who he said spent far too little time and money this year courting Hispanics.

The Democratic Party, he said, “is still learning how to win in this era of a new coalition.”

Correction: This story was updated to accurately reflect the margin of Greg Abbott’s win.

peyton.craighill@washpost.com

Katie Zezima in Colorado contributed to this report.