Sanders, Biden, maintain lead in Iowa: poll

Former Vice President Joe BidenJoe BidenBiden formally clinches Democratic presidential nomination The Memo: Job numbers boost Trump and challenge Biden Chris Wallace: Jobs numbers show 'the political resilience of Donald Trump' MORE and Sen. Bernie SandersBernie SandersBiden formally clinches Democratic presidential nomination OVERNIGHT ENERGY: Trump signs order removing environmental reviews for major projects | New Trump air rule will limit future pollution regulations, critics say | DNC climate group calls for larger federal investment on climate than Biden plan Google: Chinese and Iranian hackers targeting Biden, Trump campaigns MORE (I-Vt.) sit atop the Democratic presidential field in Iowa just one day before the first-in-the-nation caucuses, according to a new poll. 

Biden and Sanders are tied at 25 percent as the first choice nominee among likely caucusgoers, according to a CBS News poll conducted by YouGov released Sunday. 

The results largely match the CBS News poll released last week, which showed the two top candidates in the lead in the state, with Sanders holding a slight 1-point lead over Biden, within the poll’s margin of error, at 26 percent to 25 percent. 

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Former South Bend, Ind., Mayor Pete ButtigiegPete ButtigiegScaled-back Pride Month poses challenges for fundraising, outreach Biden hopes to pick VP by Aug. 1 It's as if a Trump operative infiltrated the Democratic primary process MORE maintained his third place spot at 21 percent, a one point decrease from last week. 

Sen. Elizabeth WarrenElizabeth WarrenTwitter CEO: 'Not true' that removing Trump campaign video was illegal, as president has claimed Biden formally clinches Democratic presidential nomination Warren, Pressley introduce bill to make it a crime for police officers to deny medical care to people in custody MORE had a one point increase in support, up to 16 percent. 

Sen. Amy KlobucharAmy KlobucharTwitter CEO: 'Not true' that removing Trump campaign video was illegal, as president has claimed Biden formally clinches Democratic presidential nomination Hillicon Valley: Conspiracy theories run rampant online amid Floyd protests | First lawsuit filed against Trump social media order | Snapchat to no longer promote Trump's account MORE (D-Minn.) had a 2 point decrease, down to 5 percent support. No other candidates registered more than 5 percent. 

Three of the top candidates, Sanders, Warren and Klobuchar, will miss the key event as they’re held up in Washington, D.C., as President TrumpDonald John TrumpTwitter CEO: 'Not true' that removing Trump campaign video was illegal, as president has claimed Biden formally clinches Democratic presidential nomination Barr says he didn't give 'tactical' command to clear Lafayette protesters MORE’s Senate impeachment trial presses on. A vote will be held Wednesday and the president will likely be acquitted in the GOP-controlled Senate. 

The poll surveyed 2,500 registered voters in Iowa, including 1,401 self-identified Democrats as well as registered voters who lean Democrat or plan to participate in the Democratic caucus this year. The survey was conducted between Jan. 22 and 31. The margin of error is 3.9 points in Iowa.