The Supreme Court ruled in 1992 that states can only assess sales taxes against retailers if they have a physical presence in those states. But the Court also said Congress is the body that should decide if this change should be made, since Congress regulates interstate commerce.

Twenty one years later, Heitkamp called on her new colleagues to finish the job and pass a bill allowing these taxes to be collected.

"Why we sued Quill is they were the third highest retailer of office products in my entire state," Heitkamp said on the Senate floor Tuesday. "Third highest. It's pretty remarkable. And yet they were enjoying this advantage of not having to collect sales tax.

"This issue has grown tremendously because of the explosion of Internet sales," she added. "Remote sellers are getting bigger, and our main street businesses continue to suffer, continue to struggle."

The Marketplace Fairness Act is opposed by several Republicans and even some Democrats, particularly those who live in states that have no sales tax. Opponents of the bill say the idea is essentially a new tax — many states already require people to pay sales taxes on online purchases, but few do, so the effect of the bill would be to pull out new tax revenue from consumers.

Opponents also say the bill would discriminate against online retailers, and that Congress should not be put in a spot of picking winners and losers. But Heitkamp dismissed those arguments by saying the Supreme Court has called on Congress to take a position.

"When you hear discrimination, and you hear that this is not the role of this body to take this on, understand this: it's exactly the role of this body," she said. "It is exactly the obligation that we have to level the playing field, make things fair, to respond to the needs of our community."

Heitkamp predicted that Congress would "get it done," especially in light of two recent Senate votes in which nearly three-quarters of the upper chamber supported it. But she said failure to pass this bill would not bode well for passing tougher issues.

"If we fail in moving this bill after it has such tremendous support, how do we do the tough stuff? How do we do the deficit reduction that we need to do?" she asked.

"Let's do this. Let's level the playing field. Let's make this responsive to those main street businesses who everyday struggle and are simply asking for justice."