Lewandowski -- who Trump fired this month -- touted the credentials of both Indiana Gov. Mike Pence and former House Speaker Newt Gingrich as people with strong ties to Washington, in an interview with Brianna Keilar on CNN's "State of the Union."
"If you look at Gov. Pence, he's the type of person who could help unite the party, obviously, at the convention," Lewandowski said, pointing out Pence's time as the House Republican Conference chairman. "He's the type of person who would bring a lot to the ticket."
"It's really going to come down to the personal relationship that he and Mr. Trump could have to find out if they could work well together, and if so, if that's Mr. Trump's choice, I think Gov. Pence would be a great choice for vice president," said Lewandowski, a CNN political commentator.
He emphasized the importance of Trump tapping a politician with ties to Washington, who could help advance his legislative agenda in Congress.
"Having someone who has those relationships in Washington is going to be a critical component of his presidency," he said.
Lewandowski also addressed Gingrich's comments that Trump needs to "quit screwing up."
"What you have in Newt Gingrich is someone who tells it like it is, and that's never changed," he said. "Again, you've got a person there who has extensive Washington, D.C., experience. He's been known to be able to be bipartisan and work across party lines ... Somebody who can clearly get things done in Washington -- he's the last speaker of the House to balance the budget."
He also said New Jersey Gov. Chris Christie could help Trump in battleground states, and Alabama Sen. Jeff Sessions would offer extensive relationships in Washington.
The key, Lewandowski said, is "finding the right person with the right temperament to be a good partner for Mr. Trump."
Pence addressed the swirl of vice presidential speculation Sunday night at a Fourth of July weekend event in Indiana. Including a weekend meeting with the presumptive Republican nominee at the Trump National Golf Club in New Jersey.
Pence and his wife "were able to get some personal time getting to know somebody who must be the next United States of America," the governor told reporters. "He was very interested in the progress of the state of Indiana."
Pence is up for reelection this year and said that's his primary focus.
"We're not going to get into hypotheticals" about who Trump will choose as his running mate, Pence said.