WASHINGTON - The U.S. Senate is set to begin a marathon voting session on President Donald Trump's sweeping domestic policy legislation, dubbed the "One Big, Beautiful Bill," amidst growing concerns over its impact on the national debt and divisions within the Republican party [1][2][3].

The Congressional Budget Office (CBO) released an updated estimate on Sunday, projecting that the bill would add approximately $3.3 trillion to the nation's debt over the next decade, about $800 billion more than the version passed by the House of Representatives last month [1][2].

Senate Republicans, who control 53 seats in the 100-member chamber, can only afford to lose three votes from within their party, with Vice President JD Vance potentially casting a tie-breaking vote [3]. The bill's passage remains uncertain as some GOP senators express reservations about its fiscal impact.

Senator Thom Tillis of North Carolina, who voted against advancing the legislation, announced he would not seek re-election next year, highlighting the political stakes surrounding the bill [3][5]. President Trump cautioned fiscal conservatives within his party against going "too crazy" with cost-cutting efforts, emphasizing the need for re-election [5].

The legislation combines several key elements of Trump's agenda, including:

Extension of nearly $4 trillion in tax cuts first passed in 2017 [4] Significant investments in border security and military spending [4] Substantial cuts to social safety net programs, including Medicaid [8]

Democrats have strongly criticized the bill, with Senate Minority Leader Chuck Schumer stating, "Republicans are doing something the Senate has never, never done before, deploying fake math and accounting gimmicks to hide the true cost of the bill" [12].

The CBO estimates that nearly 12 million Americans could lose health insurance coverage if the bill passes in its current form [8]. This projection has become a central point of contention in the ongoing debate.

As the July 4th deadline imposed by the Trump administration approaches, Senate Republicans are working to finalize amendments and secure enough votes for passage [7][9]. If successful, the bill will return to the House for approval of Senate changes before heading to President Trump's desk for signature [7].

The "vote-a-rama" session, during which senators can offer unlimited amendments, is scheduled to begin at 9 a.m. EDT on Monday [6]. With Democrats united in opposition and prepared to challenge the bill, the voting process could extend throughout the day [10].

As this pivotal legislation moves through Congress, its outcome will likely have significant implications for the U.S. economy, healthcare system, and President Trump's legislative legacy in his second term.