Howard Dean, a former Democratic presidential candidate and ex-governor of Vermont, issued a stern warning Monday to Sen. Bernie Sanders: Lay off Hillary Clinton, it's only helping Republicans.
"[Sanders] has got to stop with the speeches about Goldman Sachs and all this other stuff," Dean told CNBC's "Squawk Box."
"Bernie is a deeply committed guy with an ideology. He's going to want to go to the convention ... and going to give a speech about his ideals," said Dean, formerly chairman of the Democratic National Committee.
In an interview Sunday, Sanders rejected calls that he leave the race. "We intend to take the fight all the way to California," he said on ABC's "This Week." The California primary is on June 7, the final day of voter contests before the Democratic convention.
On the Republican side, Dean said he doubts the effectiveness of the alliance of Texas Sen. Ted Cruz and Ohio Gov. John Kasich against front-runner Donald Trump. "I would be shocked if this business with Kasich and Cruz works at all. Here's why: Most voters do not go to vote against somebody." Cruz and Kasich on Sunday announced a deal to stay out of each other's way in some upcoming state primaries.
However, Dean believes it will be a close call on whether Trump will get the 1,237 delegates needed to clinch the GOP presidential nomination before this summer's convention.
Trump and Clinton each hold wide leads in Tuesday's primaries in Pennsylvania and Maryland, the two biggest delegate hauls among contests in five states.
Dean unsuccessfully ran for the Democratic presidential nomination in 2004. He served as chairman of the DNC from 2005 to 2009.
Ahead of his White House run, Dean was governor of Sanders' home state from 1991 to 2003.