Story highlights Florida Sen. Marco Rubio said Saturday that he still plans to support the Republican nominee, but it's "getting harder every day"

Rubio is fighting for votes in his home state of Florida, where front-runner Donald Trump leads in polls for the crucial March 15 primary

Washington (CNN) Florida Sen. Marco Rubio said Saturday that he still plans to support the Republican nominee, but it's "getting harder every day."

The comments, made three days before critical primaries in several states, including Florida and Ohio, represent an escalation in Rubio's rhetoric, and follow a Republican debate earlier this month in which Rubio vowed to back Trump were he to become the GOP's standard-bearer.

"I still, at this moment, continue to intend to support the Republican nominee," Rubio told reporters in Largo, Florida. "But (it's) getting harder every day."

Rubio added, "I believe Donald Trump as our nominee is going to shatter and fracture the Republican Party and the conservative movement. I think it's already having that function."

The Florida Republican returned to a theme he advanced during CNN's GOP debate Thursday -- that words have consequences -- as he weighed in on the protests at Trump's Friday rally in Chicago. The Trump campaign postponed the event amid security concerns and scuffles among protesters and supporters.

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