One of Wall Street's top brokerages on Tuesday announced that its base case for President Donald Trump is impeachment.

Cowen Washington policy strategist Chris Krueger advised clients a formal accusation by the House of Representatives now seems fated and sets the stage for what he called "Bill Clinton 2.0."

Our base case is that "the House impeaches Trump, though the Senate does not convict," Krueger wrote. "Pelosi may also create a new Committee to study the Ukraine/Biden/Whistleblower issue."

"But whatever the path chosen, an impeachment vote now appears to be a question of when, not if — and more than likely by the end of this week."

House Speaker Nancy Pelosi is expected to announce a formal impeachment inquiry into President Donald Trump on Tuesday, two sources familiar with the situation tell CNBC. Earlier Tuesday, Pelosi said that Democrats are "ready," when asked whether she and her caucus will take steps toward Trump's impeachment.

"That's why I've said as soon as we have the facts, we're ready. Now we have the facts, we're ready … for later today," Pelosi said at The Atlantic Festival in response to a question about impeachment.