GOP final 4 tone down rhetoric, if not their differences

MIAMI (AP) — A surprisingly restrained Donald Trump used the latest presidential debate to send a none-too-subtle message to Republicans still wary of his insurgent candidacy: "Be smart and unify."

The candidates now charge out of Miami with four days left to make their final arguments before next week's all-important big-state presidential primaries.

In all, 367 Republican delegates are at stake Tuesday in Illinois, Missouri, North Carolina, Ohio and the Northern Mariana Islands, a delegate haul that could go a long way toward determining the GOP nominee.

Cruz, eager to cement his position as the party's last best alternative to Trump, had a string of criticisms of the GOP front-runner, too, saying flatly at one point: "His solutions don't work."

Cruz bundled together his criticisms of Trump for what he called simplistic solutions on trade and on Islamic terrorists, saying, "The answer is not to simply yell, 'China: bad, Muslim: bad."

In a meaty discussion of Social Security, Cruz and Rubio both said they'd gradually lift the retirement age for younger workers to help stabilize the system and stave off financial disaster for the program.

On that issue, the GOP front-runner couldn't resist taking a dig at the Democrats, saying he'd been watching them intensely —"even though it's a very, very boring thing to watch" — and that they weren't doing anything on Social Security.