Some Senate Democrats are bracing for President Biden's Build Back Better package to get punted into 2022, despite Democratic leaders insisting the massive social and climate bill will pass before the end of this year, Axios' Alayna Treene has learned.

Why it matters: Beyond pushing major spending legislation into a midterm year, a delay in the $1.75 trillion bill creates several technical and financial obstacles for Democrats. They include lapses in key provisions like the child tax and clean energy credits.

• Making technical fixes to the bill will be irritating for Democrats but not fatal to the legislation.
• The bigger concern is any delay will result in a smaller package.

What they're saying: "Of course there are economic issues with respect to going from one year to another," Sen. Ron Wyden (D-Ore.), chairman of the Senate Financial Services Committee, told Axios.

• Wyden said the bill must be passed no later than Dec. 28 in order for January federal support checks to be mailed to Americans.
• Sen. Ben Cardin (D-Md.), a member of Wyden's committee, agreed "there are challenges if this goes to next year."

Driving the news: The president said Friday he plans to speak with Sen. Joe Manchin (D-W.Va.), a key holdout over the legislation, early this week.

• But Manchin isn't giving any indication he's in a hurry, especially after Friday's report showing inflation running at 6.8%.
• Sen. Lindsey Graham (R-S.C.) told reporters he spoke with Manchin on Friday following the release of both the CPI report as well as the Republicans' score of the Build Back Better package — which estimates the bill would cost $3 trillion over 10 years if its programs never expire.
• “Joe Manchin came to me and he said, ‘I think this bill is full of gimmicks that these programs won’t go away, Lindsey, and if you score them, I think the bill will double,'" Graham said on "Fox News Sunday."

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House Majority Whip Jim Clyburn (D-S.C.) told "Axios on HBO" he expects Senate Democrats will find a way to get around the filibuster to pass federal voting rights legislation.

Why it matters: Protecting and expanding voting rights was a major issue Joe Biden campaigned on, but Democrats haven't been able to enact any protections nearly a year into his presidency. Clyburn predicted Congress will combine various bills into one — though he couldn't tell Axios' Alexi McCammond when.

• "It may require some jiu-jitsu, but that's not beyond the Senate to do that," he said.
• "They'll come up with some way to get around it," Clyburn added. "We had better come up with some way to get around it, because this democracy is teetering on collapse."

Between the lines: The House has passed voting rights and election reform bills but they've been modified and stuck in the Senate for months.

• The Freedom to Vote Act and the John R. Lewis Voting Rights Advancement Act are both stalled in the Senate, and Republicans killed the Democrats' For the People Act in the Senate last summer.
• "We will find a way to get these voting rights bills passed," said Clyburn, the No. 3 Democrat in the House.

Go deeper: In a wide-ranging conversation, Clyburn also said he believes Rep. Lauren Boebert (R-Colo.) should be stripped of her committee assignments — but the GOP needs to hold her accountable itself.

• "She is a member of the Republican conference. So, it's not the Democratic Party's responsibility to police Republicans," he said.

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The population of foreign-born citizens and residents in the United States has plummeted for the first time in over a decade, according to the analysis of new and experimental U.S. Census Bureau data provided to Axios' Stef Kight.

Why it matters: While the decline coincides with the spread of COVID-19, a country with an aging population like that found in the United States needs strong levels of immigration to support economic growth. More immediately, immigrants could help fill the millions of job openings in the U.S.

• The new data from the American Community Survey (ACS) also revealed the smallest decade gain in the foreign-born population since the 1960s, at 3.6 million. In comparison, the immigrant population grew by 8.8 million during the 2000s.
• The data "strongly suggest a sizeable downturn in the U.S. foreign-born population, no doubt related to a downturn in immigration in the last year" due to coronavirus restrictions, Brookings Institution demographer William Frey told Axios.

Of note: The pandemic complicated census efforts in collecting data, and the 2020 ACS results did not meet the bureau's data standards for previous years.

• Both factors explain why they are labeled "experimental."
• Former President Trump's effort to exclude undocumented populations from reapportionment numbers, though ultimately failing, may have led some immigrant populations to be wary of responding to overall U.S. Census Bureau outreach.
• This may have at least partially contributed to the lower foreign-born population numbers, Frey said.

The principal chief of the Cherokee Nation also told Russell Contreras for "Axios on HBO" it's time for Congress to make good on a 19th century treaty by seating Kim Teehee as the Cherokee people's first nonvoting U.S. House delegate.

What they're saying: "The president of the United States agreed to this 180 years ago," Chuck Hoskin Jr. said during the program's season finale. "The United States Senate did its job 180 years ago; there's one part of the government left to take action. That's the United States House of Representatives."

• Teehee was tapped by the tribe more than two years ago.

Driving the news: Hoskin and Teehee sat down for an interview at the Cherokee National Capitol in Tahlequah, Oklahoma. It's part of heavily Republican Cherokee County.

• They expressed optimism their efforts are moving in the right direction and said they have support on both sides of the aisle. "I think as long as we are willing to proactively continue to keep the ball moving, we'll get there," Teehee said.
• At the same time, Hoskin said, "I think any congressional leader or any president who campaigns on being pro-tribal sovereignty and goes back on such a basic promise, they're going to be on the opposite side of me and they're going to be on the opposite side of history. And there'll be a consequence for that."
• The Cherokee and Navajo are the two most populous Native American tribes, each with an enrollment of roughly 400,000.

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President Biden and first lady Jill Biden returned to the White House after spending the weekend in Wilmington, Delaware.