The Note: With exits, Joe Biden could be Democrats' future, but his past looms

The TAKE with Rick Klein

This is Joe Biden's moment. But it's also a moment that could hardly be less suited for him.

One could define the former vice president's brand of working-class, pragmatic, Obama-shaped Democratic politics by quoting the parade of prominent names who this week said they wouldn't run for president: Ohio Sen. Sherrod Brown, former New York City Mayor Michael Bloomberg, former Attorney General Eric Holder and Hillary Clinton herself.

A Biden-shaped gap has opened in the 2020 field, and Democrats are yearning for the candidate best-suited to take on President Donald Trump. But potential holes and pitfalls in Biden's own history are already on display, amid scrutiny that reveals no shortage of targets.

Consider that while other Democratic candidates debate reparations for descendants of slaves and Native Americans, The Washington Post unearthed this Biden quote from 1975, when Biden already was a senator: "I feel responsible for what the situation is today, for the sins of my own generation. And I'll be damned if I feel responsible to pay for what happened 300 years ago."

This week also revealed anew Democrats' unease over questions of ethnicity, religion and identity, amid wrangling and division over comments by a freshman House Democrat that were perceived as anti-Semitic.

Biden might yet be the Democrats' answer for the future. But first he may have to prove that his past is compatible with the party's present.

The RUNDOWN with MaryAlice Parks

The House Judiciary Committee started the week with a demand for documents from individuals and entities associated with Trump and the first family. In doing so, it set the stage for a potential fight with the White House that could have serious political, legal and even constitutional questions by the end of the month.

In their letters, Democrats requested all relevant information be handed over by March 18, but after the president called the move "a disgrace" and "shameful," it's hard to imagine his team tells former colleagues to comply without some real formal pushback.

The courts will likely get the final say.

Swirling around it all this week, congressional investigators also seemed to take next steps directly related to what they heard from the president's former personal lawyer, Michael Cohen. By Thursday, it was clear they had started making plans to officially ask Donald Trump Jr. to come back before Congress and face questions about whether he lied under oath about how much he knew regarding a possible Moscow real estate project.

Midweek, too, a prominent Democratic freshman announced she would introduce a resolution urging her colleagues "investigate grounds for the impeachment of Donald Trump."

While the move would diverge from the party's stated plans at this point, it will hang over all investigative work from here on out.

The TIP with John Verhovek

After a week of presidential exits, it's a weekend of opportunity for some 2020 Democrats hoping to gain traction in an already-crowded field.

With Bloomberg, Brown and Sen. Jeff Merkley all passing on potential bids, eight Democrats still finding their footing in the early stages of the race will be appearing in Austin, Texas, this weekend at South by Southwest.

Sens. Amy Klobuchar and Elizabeth Warren, Reps. Tulsi Gabbard and John Delaney, Gov. Jay Inslee, former Gov. John Hickenlooper, South Bend, Indiana, Mayor Pete Buttigieg and former secretary of Housing and Urban Development Julian Castro are all set to appear at the gathering. It's an opportunity to highlight their presidential ambitions before a younger audience.

But while the names that officially bowed out this week may open lanes for other candidates, such as Klobuchar, who seeks to highlight her Midwestern appeal in her campaign, there remains a name well-known to many Texans who have dreams of making their state a swing state in 2020.

Rep. Beto O'Rourke, who hasn't announced his presidential plans yet, isn't on the guest list for SXSW, but his presence, or lack thereof, will be felt one way or another as candidates encroach on his home turf.

THE PLAYLIST

ABC News' "Start Here" podcast. Friday morning's episode features the fate of former Trump campaign chairman Paul Manafort, with ABC News' Katherine Faulders. Plus, a big pharma trial in Boston could be a game-changer for the opioid epidemic, according to ABC "Nightline" Co-anchor Juju Chang. http://apple.co/2HPocUL

FiveThirtyEight's Politics Podcast. Every four years, a select few states -- particularly Iowa and New Hampshire -- play an outsized role in determining whom voters get to choose between for president. Those states' demographics are out of line with the makeup of the Democratic electorate. In this episode, elections analyst Geoffrey Skelley joins the FiveThirtyEight Politics podcast to discuss what other lineups might look like. https://apple.co/2mKrhcF

WHAT YOU NEED TO KNOW TODAY

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 Monday for the latest.