$2.2 trillion? $974 billion? $6 trillion? It’s not just a question of how many billions or trillions of dollars will ultimately be notched for infrastructure funding by President Joe Biden’s policymaking push and the deal-making on both sides of the aisle on Capitol Hill.

Nor is it just a question of when a pumped-up infrastructure package — gargantuan by any measure, no matter the final dollar figure — might actually get passed and signed into law.

Nope, it’s also a question of on which track this money train will end up rolling into the station. That’s the gazillion dollar question. Because the answer to it goes straight to answering the other two questions.

On the surface, it should be easy to pass an infrastructure bill with the president’s party also controlling Congress. But the Democrats hold the House by a narrow margin and the Senate only by dint of the tie-breaking vote of Vice President Kamala Harris. And in this era of hyper-partisanship, it’s not easy to drum up Republican senators willing to support a landmark Democratic initiative.

Biden’s proposal to improve public-works and safety-net programs, dubbed the American Jobs Plan, calls for spending roughly $2.2 trillion. That would include $621 billion on road, bridge, rail, port, waterway, airport, and public transit improvements, as well as building the market for electric vehicles. Broken down further, $115 billion would go to modernizing 20,000 miles of highways and other roads and $20 billion to improve road safety for all users. In addition, funds would be directed to repair the “most economically significant large bridges” and the worst 10,000 smaller bridges.

All that’s a big sell in itself. But Biden’s package would also spend hundreds of billions more, on everything from boosting manufacturing in certain sectors and investing in R&D for critical technologies to delivering nationwide high-speed broadband coverage and growing and improving the nation’s housing stock. The president wants to implement ways to bring in more taxes from corporations to raise the more than $2 trillion needed over the next 15 years.

To date, the Republican response has been to commit to spending only a fraction of what Biden seeks — and to do so without raising any taxes. On June 15, the president ended lengthy negotiations with a group of Senate Republicans when it became clear common ground could not be reached.

However, the White House signaled that Biden was still open to a plan being worked up by a bipartisan group of 10 centrist senators. That plan has been picking up more support, growing the group to number 11 Republicans, nine Democrats, and an independent who caucuses with the Democrats.

The centrists’ “skinny alternative” would spend $974 billion on infrastructure over five years. To get it that slimmed down, money would go only to fund “physical” public works projects. This bipartisan package would be funded without raising taxes on corporations or high net-worth individuals. However, some Democrats argue infrastructure spending doesn’t need to be offset anyway, because it will pay for itself over time by boosting economic activity.

But wait, there’s more: On June 17, news broke that Senate Democrats had begun privately considering an even more massive economic package that could run as high as $6 trillion.

Right now, both the somewhat fleshed-out bipartisan plan and the $6 trillion plan under consideration by leadership are moving ahead on parallel tracks. While centrist senators in both parties are pushing to gain more support for their compromise, Senate Democratic leaders are not shy about their willingness to use the fast-track budget process of reconciliation to roll over any Republican filibustering to get either President Biden’s or their own plan passed.

So, as summer comes in, that’s the state of play on moving desperately needed infrastructure legislation to the president’s desk for signing. Stay tuned for updates.

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