Mitt Romney returned to the campaign trail late Monday, targeting Hispanic voters in Miami.

Romney canceled a campaign stop in Orlando earlier in the day, with his campaign saying he “was too exhausted to make the trip” after a whirlwind weekend in which he criss-crossed Virginia, North Carolina and Wisconsin and announced his selection of Wisconsin Rep. Paul RyanPaul Davis RyanWatchdog group sues for donor list from Ryan-aligned nonprofit Terminating Budget Committees not as absurd as it sounds The writing is on the wall for bump stocks and Congress should finalize it MORE (R) as his running mate.

Democrats seized on the cancellation, with Democratic National Committee (DNC) Chairwoman Debbie Wasserman Schultz (Fla.) implying Sunday night that Romney might have canceled the event because he's worried about explaining Ryan's Medicare reform plan to Floridians.

Democrats made a similar argument after the Romney campaign announced that Ryan would be campaigning on his own in Iowa on Monday, rather than traveling to Florida with the GOP nominee. The Romney campaign dismissed the claim, saying Ryan would be campaigning in the Sunshine State in the upcoming weeks.

Romney, traveling from a morning rally in St. Augustine, arrived about 45 minutes late for the event in Miami and gave a condensed version of his stump speech, in which he assailed President Obama for what he says is a government “trying to control our lives.”

Sen. Marco RubioMarco Antonio RubioFormer Florida congressmen mull bipartisan gubernatorial run: report Winners and losers from Jim Bridenstine’s confirmation as NASA administrator GOP Senate candidates trade barbs in brutal Indiana primary MORE (R-Fla.), once considered a dark horse vice-presidential candidate, introduced Romney and lambasted Obama in his native Spanish tongue.

Romney then introduced son Craig Romney, who also addressed the crowd in Spanish.

Hispanic voters could be key in the swing states of Florida, Virginia, Colorado and Nevada, and elsewhere.

Obama has a massive lead over Romney among Hispanics, with some polls showing up to a gap of 40 percentage points between the two. The Obama administration announced earlier this year it would stop deporting illegal immigrants who come to the country at a young age.

The new policy will not grant citizenship to children who came to the United States as illegal immigrants, but will remove the threat of deportation and grant them the right to work in the United States.

The policy change accomplishes portions of the Development, Relief, and Education for Alien Minors (DREAM) Act, legislation that has stalled in Congress amid Republican opposition.

At the time, Rubio praised the policy but criticized Obama for going around Congress. Rubio had been working on his own version of the DREAM Act but has yet to release any legislative language.

Florida is a toss-up and one of 12 swing states that will be critical in determining the outcome of the 2012 election. Obama leads Romney by just over 1 percent in the Sunshine State, according to the Real Clear Politics average of polls.