WASHINGTON - Top Senate Democrats on Tuesday signaled they may have no choice but to bypass Republicans in order to advance President Joe Biden's roughly $2 trillion infrastructure package, as GOP leaders continued to attack the plan over the scope of its spending and the tax increases the White House has proposed to pay for it.

The political schisms seemed only to widen a day after Biden invited lawmakers from both parties to the White House, illustrating the significant obstacles the president faces if he hopes to craft a swift bipartisan deal. Biden has said a massive package is necessary to upgrade the country's roads, bridges and water ways as well as rebuild schools, improve broadband services, and provide more home care for the elderly.

At a weekly party lunch, Senate Majority Leader Chuck Schumer, D-N.Y., said Democrats remain committed to addressing the country's infrastructure needs with Republican support, according to party aides, who spoke on condition of anonymity to describe a private gathering. But Schumer still acknowledged that Democrats have at their disposal the ability to use a budget process, known as reconciliation, to adopt the president's so-called American Jobs Plan using only 51 votes.

Exiting the huddle, Sen. Chris Coons, D-Del., one of Biden's closest allies in Congress, predicted to reporters on Tuesday that it is "likely we will end up" relying on reconciliation in the end to pass much of the president's proposal, adding Democrats still should "first do everything we reasonably can to negotiate bipartisan bills with the other side."

Asked if Democrats broadly support that strategy, Coons replied, "We'll see. We just had a vigorous discussion. I'm very hopeful."

Senate Republicans, meanwhile, escalated their attacks on the president's infrastructure blueprint, suggesting they do not feel immediate political pressure to cut a deal. Senate Minority Leader Mitch McConnell of Kentucky and fellow party leaders took particular aim at the president's plan to finance the package by raising corporate tax rates to 28 percent from 21 percent. Such a change would partially undo tax cuts enacted during the Trump administration.

"I don't think there's going to be much if any sentiment among Senate Republicans for undoing the 2017 tax bill," McConnell said.

Joining him at a press conference, Sen. John Barrasso, R-Wyo., later blasted Biden for taking a "my way or the highway" approach to infrastructure. Echoing other Republicans, who have questioned including elements to combat climate change and other issues they see as unrelated, Barrasso slammed the White House for seeking a "slush fund of liberal spending."

The exchanges Tuesday only served to illustrate the difficult choices facing Biden as he labors to bring the parties together on a central element of his economic agenda, months after he pledged to restore political unity in Washington.

Even though Democrats and Republicans generally agree on the need to upgrade the nation's inner workings, the nascent debate has exposed deep, potentially irreconcilable divisions between them - around the role of the federal government, the size of the national debt and the state of the U.S. economy.

Seeking to build bipartisan support, Biden began earlier this month a broad outreach campaign, targeting lawmakers in Washington and state and local officials nationwide. He invited a collection of centrist members of Congress to the Oval Office on Monday, where he pledged his overtures are more than just "window dressing." In a bid to assuage Republicans, he said he is willing to negotiate changes to his corporate tax proposal and that he wasn't necessarily wedded to the idea of moving the rate to 28 percent.

Democratic lawmakers echoed the commitment to bipartisanship on Tuesday. One of the chamber's most pivotal centrist votes, Democratic Sen. Joe Manchin of West Virginia, stressed to reporters "compromise is going to happen." He praised the president for negotiating just days after he warned his own party against using tactics, including reconciliation, to override Republican opposition repeatedly.

"They can't be against everything, and they're not against everything," Manchin said.

But some of Manchin's Democratic colleagues made clear they do not intend to negotiate indefinitely. Democrats earlier this month appeared to gain a potential boost, after the Senate's parliamentarian ruled the party may be able to bring more bills under reconciliation than they first anticipated. While the exact nature of the ruling remains unclear, Democrats said they are willing to use the budget process on infrastructure - much as they had on the stimulus - if the GOP refuses to strike a deal.

"I think we want to work in a bipartisan way. But most importantly, we've got to address the needs of the American people," said Sen. Bernie Sanders, I-Vt. "And if the Republicans are not prepared to come aboard on a serious effort in terms of physical infrastructure, in terms of climate change, in terms of human infrastructure, we've got to go ahead and do it alone."

Republicans, however, continued to savage the president's infrastructure package. McConnell a day later still faulted the president for pursuing an economic agenda into "something no one voted for last year." And he took a shot at Democratic leaders, raising questions as to whether they could carry out their own threat to advance infrastructure reform on their own.

"Just lining everybody up and getting all 50 in one place, when you're not talking about covid relief, may be a challenge for them," he said.