Newly released credit card statements from the years when Senator Marco Rubio was a young Florida legislator on the fast track to leadership show a pattern of falling behind on payments while mingling personal and political spending, disclosures that reinforce the image of a politician who has long struggled with messy finances, at home and in his career.

On Saturday, Mr. Rubio’s campaign released roughly two years of charges, from 2005 and 2006, that were made to his Republican Party of Florida-issued American Express card, hoping to at last quiet accusations that he used party money to pay for trips, meals and gifts for him and his family.

Mr. Rubio, 44, has claimed all along, and his campaign repeated on Saturday, that he occasionally used the party’s card to pay for things that were not related to his job, but that he always paid American Express with his own money for those items.

Allegations about Mr. Rubio’s credit card use first surfaced in the heat of his 2010 campaign for Senate. Now, as a presidential candidate who is rising in the polls and winning financial backing from some of the party’s most prominent donors, questions about his spending practices have started to dog him again as his rivals seek to discredit him as too immature and irresponsible to be president.