Sen. Al FrankenAlan (Al) Stuart FrankenThe Hill's Morning Report — Sponsored by PhRMA — GOP lawmakers race to find an immigration fix Richard Painter puts out 'dumpster fire' in first campaign ad Bill Clinton says 'norms have changed' in society for what 'you can do to somebody against their will' MORE (D-Minn.) said Sunday that Donald TrumpDonald John TrumpCNN analyst Kirsten Powers: Melania's jacket should read 'Let them eat cake' CNN's Cuomo confronts Lewandowski over 'womp womp' remark Sessions says FBI agent Peter Strzok no longer has his security clearance MORE's final ad, which includes multiple Jewish Americans, is "something of a German Shepherd whistle."

"Well, when I saw the ad, I thought that this was something of a German Shepherd whistle, a dog whistle, to sort of the certain group of the United States," Franken told CNN's Jake Tapper on "State of the Union."

"I think that it does speak to a certain part of his alt-right base. [Steve] Bannon, I mean, who's head of Breitbart, is his chairman. They traffic in that," said Franken.

In a closing pitch to American voters, the Republican presidential nominee's campaign released a two-minute ad showing Federal Reserve Chairwoman Janet Yellen, Goldman Sachs CEO Lloyd Blankfein and George Soros. All three are Jewish.

"Trump has retweeted a lot of that sort of thing. And I think that it's an appeal to some of the worst elements in our country as a closing argument," Franken added.