Asked to explain her low approval ratings in Wisconsin on Thursday, Democratic Sen. Tammy Baldwin pointed to how "terribly polarized" the state has become and complained about the influence of the Koch brothers.

In an interview on "Morning Joe," Baldwin responded to a question about her low popularity by asserting, "We're a terribly polarized state, which I hate."

"When I started in political life running for office, people were ticket-splitters. There wasn't the partisan polarization that we see," claimed Baldwin.

As we reported earlier this month, a recent Marquette Law School poll of registered voters found Baldwin's favorability rating dipped three points over the past year, from 40 to 37 percent, while her unfavorability rating climbed from 35 to 39 percent. That shift was within the survey's margin of error, but a closer look at the poll reveals Baldwin's favorability rating was the lowest among major politicians in the Badger State. Republican Sen. Ron Johnson's favorable-to-unfavorable breakdown was at 40 percent to 30 percent, while House Speaker Paul Ryan's was 46 percent to 39 percent. President Trump and Governor Scott Walker were both viewed more favorably than Baldwin — 44 and 48 percent respectively — but had higher unfavorables as well, coming in at 48 percent and 50 percent.

While Baldwin pines for the days of ticket-splitting, it's hard to imagine which Republicans she would suggest voters support.

The senator is correct, however, to note that outside groups have already spent plenty of money to defeat her this cycle. A November analysis from the Center for Responsive Politics revealed that Baldwin was the top target of outside spending against Senate Democrats by a wide margin. "There has been $3.1 million in outside spending against Baldwin, and about $532,000 against the other Democratic incumbents combined," the report observed.

That's probably at least in part an indication of how vulnerable Baldwin is perceived to be by conservative groups and their donors, looking to target their spending in races that present strong pickup opportunities.

In her bid for a second term, Baldwin will face the winner of the Republican primary in August, pitting her against either state Sen. Leah Vukmir or businessman Kevin Nicholson.