The support of Hispanics for President Barack Obama fell in August to 48 percent, a new low, according to a survey published Thursday by Gallup.

Obama, who will deliver a speech this evening before Congress in which he will discuss new measures to reactivate job creation, is also not polling well among whites and his support among African Americans - while still quite strong, compared to other groups - is declining.

Just 33 percent of non-Hispanic whites approve of the way the president is doing his job, while his support among blacks has fallen to 84 percent.

These relatively low levels of support are a warning signal for Democrats for the 2012 elections, in which the Latino vote will be a key factor in states like New Mexico and Colorado.

Latinos, who already have expressed their disappointment with the president's immigration policy, are also moving away from other Democrats because of persistent high unemployment, a problem throughout the country but which is hitting minorities much harder.

For instance, the unemployment rate in August among Hispanics was 11.3 percent, compared with a jobless rate of 8 percent for non-Hispanic whites.

In addition, Latinos are heavily represented in construction one of the sectors that has been hit hardest by the world economic crisis and the recovery for which is proceeding very slowly.

The numbers that Gallup revealed on Thursday are also setting off alarm bells for the Democratic Party as a whole, which obtained 68 percent of the Hispanic vote in the 2008 elections.

Gallup surveyed 12,000 whites, 1,100 African Americans and 1,200 Hispanics between Aug. 1-31. The poll has a margin of error of plus/minus 1 percent.