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Business advocacy groups are going on the offensive against a financial transaction tax that's been proposed by Democrats as a way to curtail high-frequency trading and reduce the budget deficit. Groups from the political arm of the influential Koch network to the U.S. Chamber of Commerce are already gearing up for a battle with Democrats over their proposals to enact a 0.1 percent tax on securities transactions. Measures were introduced in both chambers of Congress on Tuesday by Rep. Peter DeFazio, D-Ore., and Sen. Brian Schatz, D-Hawaii. The idea is co-sponsored by more than a dozen lawmakers, including freshman firebrand Rep. Alexandria Ocasio-Cortez, D-N.Y.

The tax proposal is one of several by Democrats that target the wealthy. Ocasio-Cortez has called for a 70 percent marginal tax rate on income over $10 million. Sen. Elizabeth Warren, who is running for president in 2020, backs the idea of a wealth tax of 2 percent on households with more than $50 million in assets and 3 percent on households worth $1 billion or more. Among groups attacking the financial transactions tax proposal is Modern Markets Initiative, or MMI, which advocates for high-frequency trading. "The proposed financial transaction tax poses a threat to the very Main Street investors that the sponsors of this bill are aiming to protect," said MMI CEO Kirsten Wegner. "Particularly, pension funds, which millions of Americans rely on as a main source of income after retirement, will suffer as a result of this tax." A spokeswoman for MMI confirmed the group would be lobbying against the proposal. A person familiar with the upcoming lobbying efforts pointed to a study published in 2017 that shows the negative effects a financial transaction tax can have on pension funds. This person also said the group will be pushing out more data proving how the tax could hurt the average stockholder. The political network backed by billionaire Charles Koch is also speaking out against the legislation. In a statement first given to CNBC, a spokesman for Americans for Prosperity, or AFP, slammed lawmakers' efforts to create more taxes. "Real growth and lasting economic security comes when people and businesses are free to invest their earnings into their families, communities, and job creation," said Bill Riggs, a spokesman for AFP. "We cannot tax and spend our way into prosperity. Washington should be looking for ways to rein in reckless spending and eliminate corporate welfare, not reach back into the pockets of hardworking Americans to keep funding it."