Originally Published: 16 SEP 21 08:43 ET

Updated: 16 SEP 21 10:35 ET

By Kate Sullivan, CNN

(CNN) -- President Joe Biden will argue in a speech on Thursday that the US has reached an "inflection point" as the President pushes for his economic agenda, a White House official told CNN.

"He'll underscore that we've reached an inflection point where we have to choose whether or not we're going to perpetuate an economy where the wealthiest taxpayers and biggest corporations get to play by a set of rules they've written for themselves while middle-class families aren't given a fair shot," the official said.

The speech comes as sharp divisions in the Democratic Party threaten to bog down Biden's $3.5 trillion economic package to expand the nation's social safety net, which is the centerpiece of the President's agenda.

White House press secretary Jen Psaki tweeted Thursday morning: "Later this afternoon, @POTUS will lay out his case on the economy--and the big choice facing America at this moment: Are we going to continue with an economy that benefits the wealthy and big corporations or are we going to set the country on a path that benefits working people?"

When Biden speaks from the White House Thursday afternoon he will "lay out what's a stake in the fight to ensure that our economy delivers for middle class families, and not only for those at the top," the official said.

"He'll make the case that we simply can't revert to how things were before the pandemic, that we have to Build Back Better and deal everyone in this time as we grow the economy," the official said, referencing the slogan for Biden's economic agenda.

The official said: "He'll also argue that we don't need to reduce the cost of being rich in America; we need to lower the cost of raising a child, of prescription drugs, of taking care of an aging parent, of health care, of high-speed internet, and of hearing aids."

The $3.5 trillion plan includes funding for paid family leave, education, health care and to address the climate crisis. Senators are at odds over the price tag of the plan, the tax hikes to pay for it, the health care provisions in the proposal and climate provisions that liberals are insisting must be included.

These disagreements within the Democratic Party have raised questions about whether all 50 members of the Senate's Democratic caucus can quickly unite behind the legislation. Democrats are planning to pass this legislation using the budget reconciliation process, which only requires 50 votes and would therefore not need Republican support.

If that economic package stalls in the Senate, liberals are warning they will sink the $1.2 trillion bipartisan infrastructure bill as well, which is also key to Biden's agenda.

Congressional leaders have set an end-of-September deadline in the House to pass their massive budget bill alongside the separate bipartisan infrastructure bill.

Earlier this week, Biden focused on and touted the investments that the twin economic proposals would make to address the climate crisis. The President traveled to California and Idaho to survey damage from wildfires and argued that extreme weather events were only increasing in intensity and frequency and that the nation needed to act swiftly to address the climate crisis.

The packages contain hundreds of billions of new climate investments, which Senate Majority Leader Chuck Schumer has argued will get the US most of the way to hitting Biden's fossil-fuel emissions target of 50-52% below 2005 levels by 2030.