Today's installment of campaign-related news items from across the country.
* At an event over the weekend, former President Barack Obama expressed some concern about the "rigidity" of some in his party's base, whom he believes targets Democrats unnecessarily for "straying from purity on the issues."
* The Associated Press reported over the weekend on "a persistent group" of Sen. Bernie Sanders' (I-Vt.) supporters, who not only believe the process was deliberately stacked against him in 2016, but who are also threatening not to support the Democratic ticket in 2020 unless the Vermont senator is the nominee.
* Sen. Elizabeth Warren (D-Mass.) is unveiling a detailed new housing policy today, which she summarized in an op-ed for the Reno Gazette Journal.
* Sen. Cory Booker (D-N.J.) became the latest Democratic presidential hopeful to release his fundraising tallies from the first quarter, announcing yesterday that his campaign raised $5.1 million in the first three months of the year. That's short of the kind of numbers we've seen from some of the senator's rivals.
* A new survey from Emerson Polling found Bernie Sanders leading the Democratic field in Massachusetts with 26%, followed by former Vice President Joe Biden with 23%. Elizabeth Warren was third in her own home state with 14%, which seems problematic.
* Rep. Tim Ryan (D-Ohio) formally launched his presidential campaign over the weekend with a rally in Youngstown.
* The Republican Senate primary in Alabama is likely to be a very crowded one, as evidenced by former Auburn football coach Tommy Tuberville throwing his hat into the ring over the weekend. The GOP nominee will face incumbent Sen. Doug Jones (D) in 2020.
* And what will Democrats do if Stacey Abrams decides not to run for the U.S. Senate next year in Georgia? Former Columbus Mayor Teresa Tomlinson has created an exploratory committee, and some Dems see her as a credible contender in the race to take on incumbent Sen. David Perdue (R).