Wireless carriers are balking at U.S. regulators’ move to allow political donations by text message, a plan that could reshape the nation’s campaign finance system by giving cellphone users the ability to make instant contributions, Reuters reported.

The proposal to allow text contributions – which has been backed by the campaigns of Democratic President Barack Obama and Republican presidential candidate Mitt Romney – was approved last month by the Federal Election Commission (FEC).

It also has the support of fund-raisers and campaign finance reform groups, which told the FEC that text donations would help “empower” those who can give only a few dollars to campaigns.

This year’s campaign season has been marked by six- and seven-figure contributions from wealthy donors to groups known as “Super PACs,” or political action committees that have no limits on donations and spending.

But the wireless carriers that would oversee the donations-by-text service,  including Sprint Nextel Corp, Verizon Wireless, AT&T Inc. and T-Mobile USA Inc., have yet to get on board with the plan.

The carriers, which account for about 90 percent of the more than 330 million wireless subscriptions in the United States, are worried about an array of liability and regulatory issues they could face in handling contributions to presidential and congressional candidates, Reuters said.