The Republican senator was referring, of course, to President Obama standing in the way of Congress imposing a Kansas-style experiment on the entire country.
That's no longer a concern for GOP policymakers. On the contrary, with Donald Trump in the White House, McConnell's dream of bringing Brownback's Kansas experiment to the nation is now possible, and the administration's ridiculous new tax outline suggests many Republican officials intend to follow Topeka's lead.
With this in mind, the Kansas City Star's editorial board offered some worthwhile advice this week.
Next week, Kansas lawmakers will once again try to figure out how to cover a massive shortfall in the state's budget.
We hope President Donald Trump will be in the gallery, taking notes. That's because the president's tax plan, unveiled by the White House Wednesday, strongly resembles the disastrous tax plan passed in Kansas in 2012.
Trump wants to consolidate individual tax brackets and lower the top rate. He would eliminate some deductions and, most crucially, dramatically reduce taxes for business owners, including millions of people who own businesses but pay taxes on their profits as individuals.
Kansas Gov. Sam Brownback's 2012 tax reform blueprint was quite similar, and we know why. The same worn-out supply-side "experts" helped write both proposals.
GOP officials in Kansas, following Brownback's lead, tried a radical experiment, watched it fail, and then saw Trump and his friends pick up the same playbook. (I keep waiting for someone to tell the "it doesn't work in practice, but maybe it'll work in theory" joke.)
In fact, Slate had a good report this week noting that while the Trump White House's approach is similar to Brownback's Kansas model, the president's "plan" is in some ways worse.
While the one-page document lacked much in the way of detail, it confirmed that the president wanted to cut the tax rate on so-called "pass-through" businesses to 15 percent -- which would amount to a bigger, potentially more disastrous version of Brownback's ill-fated cuts.
"This would be Kansas on steroids," Eric Toder, co-director of the Tax Policy Center, told me.
The Kansas City Star's editorial concluded, "We do not oppose tax reform. Paying federal taxes is too complicated and too distorted by tax breaks for special interests. Taxes at all levels should be simple, low, broad and fair. But the president isn't just proposing tax reform. He also wants a trickle-down tax cut for the wealthy. Kansans know how this story ends."