Democrats gather in Motor City for second round of 2020 debates

Warren warmed up for the debate with an overflow crowd at a rally one hour south of Detroit in Toledo, Ohio, as she rolled out a new policy plan on trade.

"You want to make change?" Warren asked, as the crowd shouted their approval. "It's got to be big, structural change."

Sanders - who won the Democratic Primary here in 2016 over Hillary Clinton - has been in the Detroit area for several days, reminding supporters they need to do more to win in 2020.

"Michigan is clearly a battleground state," Sanders told supporters at a fundraiser. "Trump won it last time - together we will win Michigan."

Here's a thumbnail sketch on what to expect on Tuesday night:

+ ELIZABETH WARREN - Warren continues to show strength on the campaign trail with a constant schedule and solid crowds. In the first debate, she was the lone big name candidate, while tonight she will be joined by Sanders and Buttigieg, making for the possibility of some jabs amongst three of the top five Democrats. Warren rolls into Detroit talking about what she plans to do on trade, as she held a well attended rally in Toledo, Ohio on Monday night.

+ BERNIE SANDERS - Sanders was here in Michigan in the days before the debate, doing events focused on how Americans can save money by buying their prescription drugs in Canada. "I do not believe CEOs of pharmaceutical companies should be making tens of millions of dollars a year while working people are dying from rationing their medicine," Sanders said. Look for Sanders and Warren to possibly spar some on health care, and see whether they take flak from any of those well back in the polls.

+ PETE BUTTIGIEG - Still above the also-rans in the Democratic race, Buttigieg remains in the conversation, but clearly on a rung that's below Sanders, Warren, Biden and Haris. Maybe most importantly, Buttigieg has already qualified for the September debate, where the field will be much smaller, as many of the 20 candidates you see in Detroit probably won't make the cut for the next debate. Buttigieg's big pre-debate news was getting the endorsement of a former Democratic Congressman from Pennsylvania - otherwise, he's in the picture, but not knocking on the door of the leaders.

+ BETO O'ROURKE - The former Texas Congressman didn't exactly make a big splash in the first debate, as his poll numbers have fallen back toward the danger zone of missing the next debate in September. There was a report in recent days that O'Rourke would target Buttigieg in this debate, as O'Rourke - like a lot of other candidates on the stage - needs some kind of spark in the Democratic race for President. The big splash that O'Rourke had when he ran for Senate in 2018 has waned a bit in recent months.

+ AMY KLOBUCHAR - Once you get past Warren, Sanders and Buttigieg, the other seven Democratic candidates on the debate stage Tuesday night need the same thing - a boost - and that's certainly true with Klobuchar. The Minnesota Senator has tried in recent weeks to position herself more as the alternative moderate choice to Joe Biden, but like O'Rourke and others, Klobuchar is struggling to get out of the bottom grouping of candidates.

+ JOHN DELANEY - Not to be repetitive, but like Klobuchar, Delaney needs some kind of spark in this debate, as he also finds himself running against the more progressive urgings of his party. Delaney continues to make the rounds in Iowa - he rode in the big RAGBRAI bicycle ride last week, and has almost three dozen events scheduled in the Hawkeye State in August - but he's not really registering in this race right now, as the former Congressman from Maryland is in danger of not qualifying for the September debate in Houston.

+ JOHN HICKENLOOPER - A well regarded former Governor of Colorado, Hickenlooper is hardly making any impact on this race right now, as his more moderate brand of politics looks quaint in this time of Democrats aggressively trying to challenge the Trump Administration. Hickenlooper signaled on Monday that he might go after Elizabeth Warren in this debate, casting her various plans as too costly - something which you might hear from Republicans if she's the nominee. It's possible this could be Hickenlooper's final debate - unless something big changes.

+ TIM RYAN - The Ohio Congressman is struggling along with most others in the Democratic race to keep his head above water. Like Hickenlooper, Ryan is more to the middle of the Democratic Party, as he has long argued that his district - based around Youngstown in northeastern Ohio - is a different place than the big cities on the East and West Coast. Ryan once ran against Nancy Pelosi to oust her as Speaker - that didn't succeed. For now, his Rust Belt brand of Democratic politics is having about the same kind of success in the race for the White House.

+ STEVE BULLOCK - If you are looking for someone new in the Democratic field, then the Governor of Montana might be that person, as Steve Bullock gets on the debate stage for the first time, replacing Rep. Eric Swalwell (D-CA), who dropped out after the first debate in Miami. Any other year, Bullock could probably be a strong candidate - but those with "Governor" as their current or former title so far aren't making much of an impact on this race. Bullock certainly has a chance to get noticed on Tuesday night.

+ MARIANNE WILLIAMSON - After a first debate in which she made little headway, the headline on her campaign's email on Monday probably was the opposite of what Democratic leaders would want - "Williamson Headed Back to Detroit for Debates." In an interview with USA Today in the past week, Williamson felt she was the subject of 'mockery' after the first debate. A lot of Democrats are probably quietly hoping she fades away as quick as possible after this second debate on Tuesday night.