Two groups allied with Democratic congressional candidates have spent almost $1.8 million securing time for political ads in 2012, the organizations announced Monday. House Majority PAC, which backs Democratic candidates — and labor union Service Employees International Union announced the buys as part of a $20 million reservation spending spree nationwide. The biggest buy in Florida is $571,000 worth of reservations in Miami, followed by $440,000 in Orlando. In West Palm Beach, the two will spend a total of $378,000; in Tampa, $330,000; and in Tallahassee, House Majority PAC has reserved $76,200 worth of airtime. Each area has at least one congressional race that is expected to be in play as Democrats look to seize back the House majority they lost in the 2010 election.