There’s early proof this year that in politics, the victors get the spoils.

After more than a decade of loyalty to Republican majorities, corporate powerhouses are dramatically ramping up their giving to Democrats. And while the GOP still claims a slight edge among the deepest-pocketed corporate political action committees, Democrats have all but closed the gap.

The top 50 corporate PACs roughly split their donations between the parties for the first six months of this year — giving Democrats 48 percent, according to figures from CQ PoliticalMoneyLine. Over the past three election cycles, that same group gave Republicans $2 for every dollar they handed Democrats.

“Money follows power in this town,” said Meredith McGehee of the Campaign Legal Center.

She said companies aren’t yet flooding Democratic coffers because they first want to see whether the party is in position to strengthen its grip on the majority in the next election.

The shift in giving patterns helps explain the cash advantage Congressional Democrats have built this year. The average Democratic incumbent raised over 63 percent more from PACs during the first half of this year than during the same period in 2005, according to a recent study by the Campaign Finance Institute. That boost accounts for nearly two-thirds of the improvement in the average Democratic incumbents’ fundraising, the study found.

Democrats’ two Congressional campaign committees have a more than $30 million combined edge in available cash over their Republican rivals.

The companies adjusting their giving hail from a range of sectors — including telecom, health care, financial services and defense.

Cable giant Comcast has executed the most striking change of course. After giving Democrats slightly less than half — 47 percent — of its political money during the 2006 cycle, the company has goosed Democrats’ share to 83 percent so far this year.

Comcast spokeswoman Jenni Moyer said the swing resulted from a calendar packed with Democratic fundraising events. “Democrats came out of the chute very quickly,” she said. “Over the course of the cycle, we anticipate that COMPAC’s giving patterns will, as they always have, show a reasonable balance to the parties reflecting the makeup of the Congressional delegations in the states we serve.”

Boeing, likewise, has spun on its heels. The defense contractor upped giving to Democrats from 38 percent during the 2006 cycle to 55 percent so far this year.

In a statement, spokesman Doug Kennett said contributions “are decided on a bipartisan basis with the overriding purpose of supporting candidates and committees who share Boeing’s position on issues of importance to its business and its shareholders.”