Analysis: Rubio finally makes move on Trump — but too late?

WASHINGTON (AP) — Marco Rubio unleashed a campaign's worth of harsh criticism on Donald Trump in the final Republican debate before Tuesday's crucial primaries.

Rubio, along with most of the other GOP presidential candidates, has treated Trump with kid-gloves for months, tiptoeing around glaring questions about the real estate mogul's business record, political ideology, brash temperament and ambiguous policy proposals.

Only now, with Trump threatening to pull away from the field, did Rubio aggressively try to dismantle the billionaire businessman's grip on the Republican race, with occasional help from Texas Sen. Ted Cruz.

Rubio accused Trump of shifting his position on deportation and staffing his hotels and other businesses with foreign workers instead of Americans.

Rubio's assertive posture was sure to be cheered by the crush of Republican officials who have rallied around his campaign in recent days, desperate for the senator to become a viable alternative to Trump.

[...] when Cruz challenged Trump's conservative credentials by suggesting he's been too cozy with Democrats, the front-runner ripped the senator for being loathed by many of his Senate colleagues.

For Rubio, the squabbling was a long way from the uplifting calls for a generational change in American politics and heavy focus on his family's moving immigrant story that have been the cornerstone of his campaign.