Sen. Bernie Sanders (I-Vt.) indicated to "Axios on HBO" he's already impatient with the White House's quest for Republican support for President Biden's infrastructure package, saying. "The American people want results" and don't care if these results are achieved with bipartisan votes.

Why it matters: The Budget Committee chairman and former presidential rival can cause a lot of headaches for Biden if he so chooses.He controls the budget process Senate Democrats have used to bypass GOP opposition and pass legislation on a pure party-line vote.

• He's one of the Democrats' key progressive leaders and they can't afford to lose anyone in a 50-50 Senate.

Driving the news: To test Sanders' reaction to the White House's thinking on what has broadly been dubbed "infrastructure" — but in reality is a sweeping social welfare program that goes well beyond what is commonly understood as infrastructure — I asked the Vermont senator to react to a quote from the influential Biden aide Steve Ricchetti.

• Here's what Ricchetti told the Washington Post: "We have a little more time for the consideration of this, and the percolation of these proposals, to have broader consultation and dialogue. There's more receptivity on the Republican side to having that dialogue, and they also see the potential to reach some common ground here."
• Here's how Sanders reacted: "In general I don't agree with that. ... The bottom line is the American people want results."
• "And frankly, when people got a, you know, $1,400 check or $5,600 check for their family, they didn't say, 'Oh, I can't cash this check because it was done without any Republican votes.'"

The big picture: In the White House's view, this infrastructure package doesn't carry the "emergency" label in the way the $1.9 trillion COVID-19 relief package did. Aides think it would be harder to defend what they did on that package: ignore the Republican compromise proposal and immediately steamroll ahead with a Democrats-only package.

• Sources familiar with the White House's internal thinking say Biden's inner circle sees little downside risk in taking some time to negotiate and to split up the infrastructure package to find something palatable to enough Republicans to get 60 votes.
• The tax hikes Democrats are proposing on corporations and wealthy families — which Republicans probably will never support — are broadly popular. Biden advisers see little risk in passing a subsequent Democrat-only bill that contains these tax increases.
• If Republicans support a smaller package that fits a traditional definition of infrastructure — say, one that covers roads, bridges, ports, etc. — it will give Biden and Democrats a bipartisan "win" to carry into the 2022 midterm elections.

Between the lines: The bigger challenge for Sanders and other progressives who are impatient with this period of closed-door bipartisan discussions is that it's not only the White House that wants to take a little time to negotiate.

• Key Democrats in the Senate were frustrated that they didn't have a say in shaping the first coronavirus bill. They have made clear to Senate Majority Leader Chuck Schumer (D-N.Y.) that they will not tolerate being rubber stamps again, and want time to go through a normal process of legislating and see if they can't strike a deal with Republicans.
• This group of eager bipartisan negotiators includes Sen. Chris Coons (D-Del.), a Biden ally, Sen. Mark Warner (D-Va.) and well-known moderate Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona.
• White House press secretary Jen Psaki has said they would like to see "progress by Memorial Day" and the bill passed by the summer.

Behind the scenes: While the White House has been talking to Republicans, it has also made sure to stay closely engaged with progressives.

• Vice President Kamala Harris has talked to progressive members, including Sen. Elizabeth Warren (D-Mass.) and Reps. Pramila Jayapal (D-Wash.) and Katie Porter (D-Ohio), per a White House source.
• And Transportation Secretary Pete Buttigieg met last week with members of the Congressional Progressive Caucus.

The bottom line: If these bipartisan negotiations drag into the summer, expect progressives like Sanders to get increasingly vocal about their frustrations.

• Sanders believes the lesson of the Obama era — in which the former president held out hope of getting Republicans to support the Affordable Care Act — isthat it's foolish to let Republicans slow-walk the Democratic agenda.
• "Congress takes breaks and it's easy to obstruct," Sanders said. "The Senate is a very slow-moving process. ... I would begin, you know, starting this work immediately. If Republicans want to come on board, seriously, great. If not, we're going to do it alone."