Democrats, including House Speaker Nancy Pelosi and Senate Minority Leader Chuck Schumer, met with President Donald Trump on Tuesday to discuss an infrastructure plan.

Schumer said the two sides had agreed to craft a $2 trillion infrastructure package to fix roads, expand broadband access to rural communities, and more.

But Schumer also said the two sides did not flesh out how the package would be paid for, instead agreeing to come back together in three weeks and discuss funding.

Democrats and the GOP have very different views on how to pay for infrastructure, which could cause any bipartisan deal to stumble.

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The Democratic congressional leaders Chuck Schumer and Nancy Pelosi on Tuesday agreed with President Donald Trump on the outline of a massive investment in America's infrastructure, but what was left undecided likely dooms the ambitious piece of bipartisanship.

In a press conference outside the White House following the meeting with Trump, Schumer told reporters that the two sides had agreed in principle on a $2 trillion infrastructure package to repair roads and bridges, expand broadband-internet access to rural Americans, and more.

"We agreed on a number, which was very, very, good, $2 trillion for infrastructure," Schumer said. "Originally, we had started a little lower and even the president was eager to push it up to $2 trillion."

But the rare moment of bipartisan consensus also comes with a major catch: The two sides did not agree on how to pay for the plan and instead decided to meet again in three weeks to address the critical issue.

This leaves the biggest issue — and a massive potential roadblock to a deal — undecided.

Trump. Susan Walsh/AP Images

Democrats, GOP don't agree on how to fund infrastructure

If the infrastructure issue and Trump's desire for a massive investment sound familiar, that's because they are. Trump has pitched an expansive infrastructure bill since his candidacy in 2016 and rolled out a massive proposal in January 2018 to fund improvements.

But despite agreement from Democrats that such an investment would be beneficial to the country, none of the ideas have ever gotten off the ground. The major sticking point that has doomed any effort on the infrastructure front has always been how to pay for the improvements.

Democrats staunchly believe that investment should be funded primarily through public expenditures, meaning the government should put up the money to pay for the fixes.

By contrast, Republicans and Trump's previous plans have all called for a small amount of seed capital from the government that would incentivize private companies to make the rest of the investment.

For instance, Trump's $1.5 trillion infrastructure plan released in 2018 called for just $200 billion in government funds to be put toward improvements and another $1.3 trillion in money, mainly through partnerships with private firms. In turn, the plan wanted all projects to generate revenue and generally be managed by private firms.

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Democrats, including Schumer, contend that infrastructure investment should be done primarily with public funds and have suggested that the plan could offset some of its costs through a rollback of parts of the GOP tax law, which was a major legislative victory for Trump and probably untouchable for the president.

There are, of course, a slew of other reasons that Democrats and Trump won't be able to get an ambitious infrastructure plan to the finish line. But a hang-up over funding could be the biggest divide for the GOP and Democrats to cross.

However, there may be a way forward.

According to Axios, Trump despised the 2018 infrastructure plan and has told advisers that private-public partnerships don't work. The president actually wants to sink public funds into the infrastructure idea.

That would draw the ire of members of Trump's own party, especially those who say they are concerned about the increasing federal deficit. So even if Democrats can get Trump on their side, the GOP-controlled Senate would become an issue.