WASHINGTON — With a powerful new tool, Senate Majority Leader Chuck Schumer has fresh options for potentially advancing President Joe Biden’s infrastructure package and other priorities past Republican obstruction in the 50-50 split Senate.

Republicans still pledge to do all they can to halt Biden, but an official parliamentarian’s opinion this week is a potential game-changer. It unleashes multiple options for Democrats to advance parts of Biden’s agenda — including immigration and Medicare legislation — with 51 votes in the 100-member Senate rather than the 60 typically needed to move major legislation past filibuster threats.

There has been talk of trying to change the filibuster rules, but that would be a very heavy political lift in the divided and tradition-devoted Senate.

The White House was heartened by the parliamentarian’s ruling but isn’t giving up on support from some Republicans, despite their strong opposition to paying for much of the infrastructure plan with a corporate tax increase. The president, said press secretary Jen Psaki, “continues to believe ... that there is a bipartisan path forward.”

However, it is clear that the deep partisan polarization in Washington has led to a new era in legislating. The seasoned policy wonks on Capitol Hill are digging deep into the procedural toolbox to find ways around the gridlock that typically leaves Congress at a standstill.

While congressional Democrats had already planned on resorting to “budget reconciliation,” a special, budget-linked procedure with a 51-vote threshold to pass parts of Biden’s $2.3 trillion infrastructure package, the parliamentarian’s ruling opens the door to using it on certain other priorities.

Using the budget rules to pass sweeping legislation on a party line vote is not new. Congress used the budget reconciliation process last month to approve Biden’s sweeping $1.9 trillion COVID-19 rescue despite no Republican support.

But the opinion by the nonpartisan Senate parliamentarian, Elizabeth McDonough, late Monday means the process can potentially be used multiple times this year -- rather than just two or three times, as had been expected.

Typically, Congress has one budget resolution every fiscal year, or two each calendar year since the fiscal year starts Oct. 1. The parliamentarian signaled if the annual budget resolution is revised, the process can be used again.

That’s a quicker route to passage for certain Biden priorities than gutting the Senate filibuster.