US Senator Cory Booker has set a new record for the longest speech ever delivered in the Senate, speaking for 25 hours and four minutes.

The New Jersey Democrat used the marathon speech as a symbolic protest against President Donald Trump, calling the current political climate a "grave and urgent" moment in American history. Although not a formal filibuster -- designed to obstruct legislation -- it significantly delayed Senate proceedings.

Under Senate rules, such speeches require the speaker to remain standing and forgo bathroom breaks. The previous record of 24 hours and 18 minutes was set in 1957 by Republican Senator Strom Thurmond, who opposed the Civil Rights Act.

Booker, 55, began his speech at 7pm on Monday and concluded at 8:06pm on Tuesday, stating he would continue speaking for as long as physically possible. Throughout his address, he read letters from constituents affected by Trump’s policies, recited poetry, discussed sports, and engaged in discussions with fellow senators.

The senator, who is African-American, reflected on his personal history as a descendant of both slaves and slave-owners, emphasizing the power of the people over individuals in leadership.

"I'm here because as powerful as he was, the people are more powerful," he said, referring to segregationist Thurmond's record-setting address 68 years ago.

As he approached the record-breaking mark, Booker joked about needing to "deal with some of the biological urgencies I'm feeling". To ease the strain, he took questions from colleagues, including Senate Minority Leader Chuck Schumer, Senator Dick Durbin, and Senator Kirsten Gillibrand.

The Democratic Party, currently in the minority in both Congress and the White House, rallied behind Booker's effort. His speech now stands as the longest since Texas Senator Ted Cruz’s 21-hour filibuster against Obamacare in 2013.

Cruz, reflecting on his own experience, told CBS that such speeches are physically demanding. During his filibuster, he wore comfortable shoes and limited water intake, following a strategy he described as "nothing in, nothing out."