The Republican and Democratic parties have each received nearly $18 million in taxpayer money for next year's political conventions and could receive another infusion of cash by early next year.

The sums were reported this week by the Federal Election Commission and show how public financing for presidential elections has grown over the years -- though the political parties also raise copious private money for the conventions.

Rep. Tom Cole, R-Okla., who earlier this year authored a bill calling for the elimination of public campaign financing, on Wednesday renewed his call for scrapping the system. Public financing is available to support both the conventions and general election campaigns.

"It's outrageous for the government to write $17 million checks to political parties when we're facing trillion-dollar deficits," Cole said in a written statement, describing the system as "an outdated, wasteful program."

The House voted 239-160 earlier this year -- with 10 Democrats supporting -- for Cole's bill to end the system that supports both the conventions and general election campaigns. Cole on Wednesday urged the Senate to follow suit. He also suggested the bipartisan committee tasked with reducing the deficit take aim at the public-financing system to save taxpayers millions.

But advocates of the system say it's a critical way to reduce the influence private donors have in the process.

"There's a concern that if party conventions are funded through private donations exclusively, they'll become an easy way for soft money to make it into the system," said Adam Skaggs, senior counsel with the Brennan Center for Justice. Soft money refers to contributions that are largely unregulated.

Skaggs suggested it would be appropriate to consider more restrictions on private contributions rather than do away with the public system.

Common Cause spokeswoman Mary Boyle also said the private contribution system should be "looked at," saying it's a way for corporations to "cozy up" to the parties.

She said that, ideally, only public money would be used to fund the convention committees -- which would then be compelled to put on less elaborate, less expensive affairs.

The public support makes up only a fraction of what the convention committees raise for their respective events. While the committees do not yet have to file their reports on private donations for the 2012 cycle, documents on the 2008 election demonstrate how important private funding is for the parties.

A joint study from the Center for Responsive Politics and Campaign Finance Institute at the time showed the two parties raised a total of $118 million, separate from the money they received from the federal government. On the Democratic side, big donors included labor groups like the Service Employees International Union and National Education Association. On the Republican side, big banks donated most of their $2.9 million in convention contribution to the Republicans. Bailed-out American International Group split $1.5 million between the two parties, according to the study.

For 2012, Duke Energy Corp. has already offered a guarantee for a $10 million line of credit for the Democratic convention, as fundraising on both sides gets under way.

Brendan Glavin, data manager with the Campaign Finance Institute, said the whole system is "problematic" -- both the private and public funding components.

He said the private funding component allows for contributions "that otherwise wouldn't be allowed" in the normal election process.

But he questioned whether public funding is still needed, considering how much is raised privately.

The cap on public convention support was originally set at $2 million in 1974. The ceiling eventually grew to $4 million, along with an adjustment for inflation. As a result, public funding for each party's convention surpassed the $10 million mark in the early 1990s and was at $16.8 million for the 2008 cycle.

The Federal Election Commission announced this week that each major party has received $17.7 million for the 2012 conventions, and that another $600,000 or so could be forked over in early 2012.

In exchange for the money, the respective political committees are held to certain rules on spending limits and disclosure reports. The funding reforms were enacted after the Watergate scandal to minimize the influence of corporate funding.

The program is supported by an optional $3 to $6 fee taxpayers can pay on their returns, to go to the Presidential Election Campaign Fund.

The Republicans are holding their 2012 convention in Tampa, Fla. The Democrats are holding theirs in Charlotte, N.C.