One of the biggest food fights in US government is about to start on the Senate floor in Washington DC, and senator Bernie Sanders has launched the first attack.

The fight is over bipartisan legislation that would give food companies three paths for complying with rules for GMO labeling on food products. The bill would let companies pick one of the following options:

Use a government-sanctioned US Department of Agriculture (USDA) symbol on packaging.

Print a label using plain language.

Print a QR code on food packaging that shoppers can scan.

The food industry, including the Grocery Manufacturers Association, a powerful Washington lobbying group, has been gunning for the QR code option for months. But critics, including the nonprofit Center for Food Safety, claim it would be confusing for consumers, who for a variety of reasons haven’t gotten into the habit of regularly scanning QR codes.

Enter Vermont’s senior senator, who on July 6 dispatched this pithy tweet to his 2.2 million Twitter followers shortly before the Senate went into session:

These are skills no doubt honed during a presidential campaign that put Sanders up against some of the best social media trolls in the business.

I downloaded a QR code reader to see if the QR code in the tweet was real. It is, and it links to a statement posted on Sanders website, in which he laid out his reasons for opposing the bill. If you don’t have a QR code reader (and there’s a good chance of that), save yourself some time and take a look at Sanders’ statement here.

The Senate bill got the 60 votes needed to invoke cloture, which officially ends debate and moves the matter to a vote, which could be held as early as Thursday (July 7).

Need to get caught up on the GMO legislation drama? Here’s a quick rundown of what’s been going on:

Vermont took a stand

Rather than than wait for federal lawmakers to hash out a nationwide GMO labeling law, Vermont in 2014 enacted a law requiring labels on products containing genetically engineered ingredients. That law went into effect July 1.

Food companies hated it

Food companies fought tooth-and-nail to beat the law and failed. Their argument was straightforward: If one relatively small state requires food to be labeled a certain way, it sets up the chance that other states could enact their own laws, creating a patchwork of complicated requirements that could become expensive for the food companies to meet.

So lawmakers set to work

To avoid such a patchwork, Senate lawmakers have been trying to pull together a federal standard that would override any one state law. Of course, that’s easier said than done. The bill in question has been years in the making, and is the product of an intense bipartisan effort between Kansas Republican Pat Roberts and Michigan Democrat Debbie Stabenow, the chairman and ranking member, respectively, of the Senate Agriculture Committee. This is the bill that lawmakers are debating this week, and the one Sanders, seeking to protect the standards required now in Vermont, is opposed to.

This post has been updated to reflect the results of the Senate cloture vote on July 6.