The Note: Buttigieg takes hold in center of 2020 field Buttigieg has found himself in the middle of several overlapping conversations.

The TAKE with Rick Klein

Mayor Pete Buttigieg has found himself in the middle of several overlapping conversations. For a candidate billing himself as middle-of-the-country centrist, that's not a bad place to be -- or a bad time to be there.

A few recent Iowa polls are now putting Buttigieg in the mix in the first-voting state. He is a veteran at a time that foreign policy is a central issue; and young and Midwestern at a time that the race looks older and coastal. Buttigieg is intriguing to some Democrats who worry about former Vice President Joe Biden's long-term viability.

He is also contrasting himself with a new front-runner, Sen. Elizabeth Warren, on health care policy and even the role of Facebook, with Mark Zuckerberg set to return to Capitol Hill on Wednesday.

Buttigieg went on the attack last night on "The Tonight Show" when he spoke to Jimmy Fallon about Syria. “It's just a bad day for America when our country can't be relied on to keep its word ... Not only is it undermining stability in Syria, it's undermining the honor of American soldiers who feel now that their honor has been taken away. And when you take away soldiers honor you're taking away the most important thing and it's taking away our country's honor, it makes the world a more dangerous place."

Buttigieg's campaign has been searching for a next act. A week after a solid debate, a race with a seemingly fixed top tier of three candidates is close to adding a fourth major contender.

The RUNDOWN with Kendall Karson

Minted front-runner status comes at a cost in the Democratic primary and Warren got a taste of it in the fourth Democratic debate, when she became her rivals' primary target, specifically over health care. But Warren dodged and deflected in the Ohio matchup, and now -- back on the trail -- she is digging into the details of her health care stance.

"We need to talk about the cost. And I plan, over the next few weeks, to put out a plan that talks about, specifically, the cost of ‘Medicare for All' and specifically, how we pay for it," Warren said at a town hall in Indianola, Iowa on Sunday, announcing that she will put forward a proposal detailing how to pay for Medicare for All, while still maintaining her support for Sen. Bernie Sanders' signature proposal.

Amid more scrutiny on her campaign that comes with a rise in polling and fundraising, the former Harvard professor has hedged on questions of how to pay for Medicare for All without raising middle-class taxes dozens of times over the past several months.

On Monday, once again pressed on why she hasn't put out a plan to cover the cost of the health care plan sooner, Warren stood by her long-game approach.

"I've been working on the financing part of this for a long time now, and reaching out to different experts and putting those pieces together. I was an original co-sponsor of Medicare for All when Bernie put the bill out. ... I'm still working on it and it will be out soon," she said.

The TIP with Lissette Rodriguez

The end of Julián Castro's presidential run may be in sight. Left with less than a month to secure four qualifying polls to make the November debate, his campaign has made a fundraising plea for $800,000 by Oct. 31. If he doesn't make that goal, he "will have no choice but to end my race for President" he wrote in an email to supporters.

But it's not the first time the former housing and urban development secretary has warned that he may need to call it quits. Less than a month ago, the Castro campaign sent out a fundraising email that read, "if I don't make the next debate stage, it will be the end of my campaign."

The team later had to walk back that language, saying what they meant to convey was that the debate was critical to his success and that they were counting on the support of grassroots donors to get them there. However, his latest fundraising numbers suggest he didn't have the grassroots support he was looking for either. Castro took in $3.5 million in the third quarter, with the least amount of cash on hand -- only $672,000 -- of the top 11 candidates at last week's debate.

While Castro isn't the first candidate to make a short-term plea for cash, i.e. Sen. Cory Booker asking for $1.7 million in 10 days and Beto O'Rourke asking for $2 million in six weeks, he did take a slight dig at those candidates just days ago, telling ABC News that while other campaigns were being "creative" with their fundraising, his team was "focused on a steady, strong campaign with a foundation to it" in which they didn't overspend on a top-heavy staff.

That leaves two questions. Will $800,000 actually make a difference if he still doesn't get the qualifying polls and visibility he needs? Or will the $800,000 ask give him the visibility he's been looking for?

ONE MORE THING

The man who was responsible for providing legal advice to former President Bill Clinton during his impeachment inquiry told ABC News' "The Investigation" podcast that President Donald Trump's strategy to combat his own impeachment inquiry is "doing enormous damage to him."

"When you're in a hole, stop digging," said Greg Craig, who served as assistant to the president and special counsel during the Clinton impeachment, directing his comments toward the president and his personal lawyer Rudy Giuliani.

THE PLAYLIST

ABC News' "Start Here" Podcast. Tuesday morning's episode features ABC News Chief Global Affairs correspondent Martha Raddatz, who explains why the U.S. may keep some troops behind in Syria after all. Then, ABC News' Katherine Faulders tees up another key deposition in the impeachment inquiry set for Tuesday morning. http://apple.co/2HPocUL

ABC News' "The Investigation" podcast. As Congressional committees continue their investigations as part of the impeachment inquiry, "The Investigation" co-hosts Chris Vlasto and John Santucci sit down with veteran attorney Greg Craig, who represented President Bill Clinton during his senate impeachment trial. https://apple.co/2BlcX0N

WHAT YOU NEED TO KNOW TODAY

Former Rep. Beto O'Rourke, D-Texas, will appear on ABC News Live's "The Briefing Room" at 3:30 p.m.

President Donald Trump has lunch with Secretary of State Mike Pompeo at 12:45 p.m. at the White House.

William Taylor, the acting U.S. ambassador to Ukraine, is expected to appear before House impeachment investigators on Capitol Hill.

Sen. Kamala Harris, D-Calif., attends a house party in Cedar Rapids, Iowa, at 10:35 a.m. (CDT) on Sunday. She then participates in a Mamas for Kamala Play Date event in Vinton at 1 p.m. Later, she hosts a town hall in Iowa City at 5:45 p.m.

Marianne Williamson speaks at the University of Iowa at noon in Iowa City, Iowa. Later she speaks at Cornell College at 3:30 p.m. in Mount Vernon. She then hosts a meet-and-greet event at 6:30 p.m. at Kae Apothecary and Wellness Space in Mount Vernon.

Sen. Elizabeth Warren, D-Mass., participates in a small business walking tour in Waterloo, Iowa, at 2 p.m. (CDT). She then hosts a town hall in Cedar Falls, Iowa, at 4:15 p.m.

South Bend, Indiana, Mayor Pete Buttigieg holds a campaign rally at 4:30 p.m. (PDT) in Las Vegas. Later he speaks at a Celebrate Progress Event at 7:15 p.m.

Andrew Yang attends Hollis Democrats' Harvest Fundraiser in Hollis, Iowa, at 6 p.m.

Former Rep. Joe Sestak, D-Pa., speaks at the Harvest Festival Dinner in Hollis, New Hampshire, beginning at 7 p.m. Later he attends a town meeting organized by local Democrats in Dunbarton at 8:10 p.m.

Former Rep. Mark Sanford, R-S.C., continues his 11-state road trip stopping in Las Vegas and Los Angeles.

Download the ABC News app and select "The Note" as an item of interest to receive the day's sharpest political analysis.

The Note is a daily ABC News feature that highlights the key political moments of the day ahead. Please check back tomorrow for the latest.