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Charlie Riedel, Associated Press
Republican presidential candidate, Rep. Ron Paul, R-Texas has his photo taken with Alaine Olthafer-Lange and her 3-month-old daughter Heidi Lange during a campaign stop in Dubuque, Iowa, Thursday, Dec. 22, 2011.

IOWA CITY, Iowa — Ron Paul's strong campaign organization in Iowa has been aided by two nonprofit groups that allowed him to keep his aides employed, his volunteers engaged and his ideas alive between White House bids.

The nonprofits blur the line between his campaign and issue advocacy in a way experts say runs afoul of the spirit and perhaps the letter of tax and campaign finance law.

When Paul dropped out of the 2008 presidential campaign, he urged supporters to continue their fight by joining his new group, the Campaign for Liberty. Another group was formed to continue outreach to college students.

The groups insist their mission is to fight for libertarian causes. But aides acknowledge they have indirectly helped Paul's campaign by training activists and educating Americans about Paul's ideas.