Both parties, as well as campaign finance reform advocates, say the move will allow Americans of modest means to play a greater role in a democratic process dominated this election cycle by billionaires and multimillionaires and political organizations such as super PACs that may raise and spend money without restriction.

The decision will take effect immediately, although it may be days or weeks before the system is fully functional. Individual phone numbers will be capped at $50 worth of donations per billing cycle per political candidate or committee.

Texting a political donation will be akin to what many charities already do in asking people to text a short message to a five-digit number in support of a cause.

Upon doing so, a donor has a fixed amount of money — often $10, sometimes more — charged to his or her account. The process takes a matter of seconds in contrast to comparatively clunkier methods, such as writing a paper check or using a credit card after filling out an online donation form.

A presidential or congressional candidate, lording over a high-energy rally, might urge a throng of hundreds or thousands to pull out their phones and contribute that very moment. Instant cash.

Likewise, political action committees could solicit text message-based donations through their broadcast and online advertisements, giving them easy streams of political cash.

From the outset, most of the six FEC commissioners — both those appointed by Republicans and Democrats — expressed support for the donations-by-text concept. But Democrat-appointed commissioners raised several concerns about the logistics surrounding donations by text, such as how to prevent scofflaws and foreign nationals from exceeding contribution limits or using multiple, disposable cellphones in order to make illegal donations.

Lawyers for companies Red Blue T, ArmourMedia and m-Qube, which this year asked the FEC to consider the matter, largely allayed these and other concerns commissioners had about contribution accounting.

Political campaigns and committees also have the ability to “block text message contributions from any cellphone at any time for any reason,” m-Qube attorneys Craig Engle and Brett G. Kappel told the FEC.

If people really wanted to pour large amounts of money into political campaigns, “you’d probably just start a super PAC — you wouldn’t buy a bunch of cellphones,” said Commissioner Cynthia Bauerly (D).

Campaign finance advocates on both sides of the spectrum say the decision is long in coming.

“Nearly everyone agrees that allowing small contributions to be made by text poses little risk of corruption and will help average Americans, especially younger voters, get more involved in politics,” said Allen Dickerson of the pro-campaign finance deregulation Center for Competitive Politics.

The FEC “did the right thing today,” said Nick Nyhart, president of political money reform group Public Campaign, one of 10 reform organizations that petitioned the commission to approve the case. “In the age of six- and seven-figure donations to super PACs, we should be doing more to encourage policies like this that enhance the roleof small-dollar donors in our political process. This is a step in the right direction.”

Fifteen Democratic members of Congress also jointly signed a letter earlier this month asking commissioners to approve the case.

In official comments to the FEC, the presidential campaigns of both Barack Obama and Mitt Romney expressed support for political donations by text.

Monday’s decision, which the FEC’s commissioners reached by tally vote without conducting another public meeting, took several years and two separate cases to reach.

In 2010, the FEC considered a political donation-by-text case, but ruled against the petitioners.

Since then, however, it’s shown greater willingness to approve new methods of making political donations, including shopping rewards programs in which users may transfer rebates to political causes.

And although it took commissioners two lengthy public sessions, two delayed votes and dozens of questions, they approved the case on the last day that they had, by rule, to render a decision.