Democratic Leaders need to message heavily about corruption for sure but tie it to an economic message.

Such as:

The economy is terrible, there are no factories being built and no new jobs coming to America, but Trump is sure helping himself out by taking bribes and gifts from Qatar, Syria, Pakistan, UAE and Saudi Arabia, and if you didn't know they were the main sponsors of terrorism in the world that brought us Hamas, Al Qaida, and more notably 9/11.

Mass Corruption -> Economics -> Increasing the Deficient on Tax Cuts -> Cutting Programs -> Does Not Help America -> Benefits Only Trump Family and his Supporters