Hillary Clinton has opened her lead against Donald Trump in three key-battleground states, including two that have long been considered Republican strongholds, according to a new Quinnipiac University State poll.

In Virginia, Clinton tops Trump among likely voters by 12 points — 50 percent-38 percent. She also has a double-digit lead in Colorado, 49-39.

In Iowa — a state considered too close to call — she leads by 3 points, 47-44.

According to Peter Brown, assistant director of the poll, Republicans should be worried because Clinton could take Virginia and Colorado in a landslide, even though those states leaned Republican a few years ago, and before that were both considered GOP strongholds.

Meanwhile, Trump struggles in Colorado because of its growing Hispanic population. Brown explained that in Iowa, it's much closer because the state has a smaller minority population.

Clinton leads among women by 18 points in Colorado, 19 points in Iowa, and 25 points in Virginia. Trump's lead with men is 14 percent points in Iowa, but he and Clinton are essentially tied among men in Virginia and Colorado.

The survey was conducted from Aug. 9 to 16 among 830 likely voters in Colorado and 846 likely voters in Iowa, both with a margin of error of plus or minus 3.4 percentage points. Among the 808 likely voters in Virginia, the margin of error is plus or minus 3.5 percentage points.