In advance of having to collect online state sales tax, Amazon.com said Tuesday that at the end of the month it will sever ties with its Minnesota-based affiliate websites that receive a fee for referring shoppers to the retail giant’s online store.

The move comes less than a month after Gov. Mark Dayton signed a law requiring certain online businesses with a physical presence or affiliates in Minnesota to charge sales tax on items it sells to the state’s residents. The law takes effect July 1, one day after Amazon’s move.

Yet Amazon is not opposed to collecting online sales tax — just not on a state-by-state basis.

“While we oppose this unconstitutional state legislation, we strongly support the federal Marketplace Fairness Act now pending before Congress,” Amazon told its affiliates in an email. “Congressional legislation is the only way to create a simplified, constitutional framework to resolve interstate sales tax issues, and it would allow us to reopen our associates program to Minnesota residents.”

Amazon representatives could not be reached for further comment Tuesday.

Online sales taxes are not new. They are supposed to be paid to the state voluntarily by consumers who buy goods online. But most consumers do not pay the taxes. Many don’t even know about them.

What’s new in Minnesota is the law requiring the vendor, such as Amazon, to collect the taxes upon purchase. By ending the affiliate relationships, Amazon exempts itself from that obligation, but that doesn’t exempt the consumer.

Amazon also has ended affiliate relationships in other states that have passed similar laws, such as California.

There are about 5,200 affiliates in Minnesota that make money from online advertising, said Rebecca Madigan, executive director of the Performance Marketing Association, a trade group that represents the affiliates.

Those 5,200 don’t just work with Amazon.com. They may be affiliates of Cabela’s or Blue Nile or other sizable Internet retailers.

The change in Minnesota’s state law affects about 1,000 online retailers — not just Amazon.com — Madigan said. The 5,200 affiliates in Minnesota generated a total of about $500 million worth of business in 2012 and paid about $35 million in state income tax, she said.

Because of the new online sales tax law, “the state is actually going to lose money” from the affiliates, Madigan said, “because they’ll lose that income tax revenue.” About three-quarters of the businesses have fewer than four employees.

Amazon affiliates such as Maple Grove-based Carrie Rocha, who blogs about consumer bargains at Pocketyourdollars.com, direct shoppers to Amazon and are paid a commission on purchases made by those they refer.

Although Rocha has affiliate relationships with hundreds of retail websites, Amazon is the largest, making up more than 10 percent of her affiliate revenue. Other retail websites have ended their affiliations with Rocha, too, including Overstock.com, because of the new law.

“Amazon is the big dog,” Rocha said. “But I’ve been fired by other online retailers already. … I’ve been getting these emails since this was signed into law.”

She is anticipating a 15 percent to 25 percent drop in total revenue when Minnesota’s online sales tax law takes effect.

Affiliate referrals make up about half of her website’s revenue, while impression-based advertising — money received for ads on her webpage — makes up the other half. Rocha said her relationship with Amazon accounts for about 6 percent of her total revenue.

Pocketyourdollars.com logs about 1 million unique viewers a year. Rocha is hoping she will not be forced to reduce the hours of her eight part-time employees and she is working to launch another consumer-oriented website to compensate for the lost revenue.

A total of 12 states have now passed laws to collect online sales taxes, but “they just don’t work,” said Madigan of the Performance Marketing Association. “They won’t convince an out-of-state retailer to collect the sales tax.”

Amazon may take a hit in Minnesota on its revenue by cutting off the affiliates, she said. “But they can work with Internet affiliates in other states” to serve customers in Minnesota, she said.

The solution, she said, is the federal legislation requiring the collection of sales taxes on online purchases, which has passed the U.S. Senate and is now awaiting action by the House. That’s the Marketplace Fairness Act cited in Amazon’s statement.

“I think we’ll get it done this year,” she said.

John Welbes contributed to this story.