In 1982, Deutsch was elected for the first of five two-year terms in the Florida House of Representatives, where he wrote legislation protecting seniors from illegal nursing home evictions.

Although Deutsch consistently led opinion polls in the Miami-Fort Lauderdale metropolitan area, and had the largest amount of cash on hand for most of the race, he lagged in statewide opinion polls behind rival Betty Castor, whose fundraising dramatically accelerated during the summer of 2004 with the help of EMILY's List, which contributed close to $4.5 million in television and advertising dollars.

The Castor campaign was accused of inappropriate coordination with EMILY's List, and a lawsuit was filed with the Federal Election Commission.

In June 2004, he hired Sanford Dickert, CTO for the John Kerry for President Campaign, as his Director of Internet Strategy.

On March 2, 2006, Al-Arian entered a guilty plea to a charge of conspiracy to help the Palestinian Islamic Jihad, a "specially designated terrorist" organization.

Later in the campaign, Senator Bob Graham and Florida’s other senator Bill Nelson proposed a pledge between Castor, Deutsch, and Alex Penelas to refrain from negative campaigning; Deutsch agreed to the pledge, but added a clause allowing him to raise "legitimate" electability issues.

Deutsch was unable to run for reelection to the House because of his Senate campaign, and was succeeded by the new Democratic candidate, Debbie Wasserman Schultz.