WASHINGTON, Jan. 20 (CNA) - Three new senators were sworn into office on Wednesday (Jan 20) after President Joe Biden's inauguration, securing the majority for Democrats in the Senate and across a unified government to tackle the new president's agenda at a time of unprecedented national challenges.

Vice President Kamala Harris drew applause as she entered the chamber to deliver the oath of office to the new Democratic senators - Jon Ossoff, Raphael Warnock and Alex Padilla - just hours after taking her own oath at the Capitol alongside Biden.

The three Democrats join a Senate narrowly split 50-50 between the parties, but giving Democrats the majority with Harris able to cast the tie-breaking vote.

The new arrangement makes Democratic Senator Chuck Schumer the majority leader, with Republican Mitch McConnell demoted to minority leader.

“Today, America is turning over a new leaf. We are turning the page on the last four years, we're going to reunite the country, defeat COVID-19, rush economic relief to the people,” Ossoff told reporters earlier at the Capitol. “That’s what they sent us here to do.”

Ossoff, a former congressional aide and investigative journalist, and Warnock, a pastor from the late Martin Luther King Jr's church in Atlanta, won runoff elections in Georgia this month, defeating two Republicans.

Warnock, 51, who never before held political office, is the first black senator to represent Georgia.

Ossoff, 33, is the youngest senator sworn in to the Senate since Biden, who took office in 1973 at the age of 30. The first Jewish senator from Georgia, Ossoff was sworn in on a book of Hebrew scripture that belonged to Atlanta Rabbi Jacob Rothschild, a close ally of King.

Padilla, California's first Latino senator, was appointed by the state's governor to fill Harris' Senate seat after she resigned on Monday to assume her new role - drawing chuckles from the vice president as she read aloud the official documentation.

The 47-year-old Padilla has been California's secretary of state since 2015. He previously served in the state Senate and spent over seven years on the Los Angeles City Council, five of them as council president.

Taken together, their arrival gives Democrats for the first time in a decade control of the Senate, the House and the White House, as Biden faces the unparalleled challenges of the COVID-19 crisis and its economic fallout, and the nation's painful political divisions from the deadly Jan 6 siege of the Capitol by a mob loyal to Donald Trump.

The pandemic has claimed 400,000 American lives, and Biden is proposing a US$1.9 trillion recovery package to distribute vaccines and shore up an economy struggling from the virus shutdowns.

At the same time, the Senate is about to launch an impeachment trial of Trump, charged by the House of inciting the insurrection at the Capitol as rioters tried to interrupt the Electoral College tally and overturn Biden's election. The Senate will need to confirm Biden's Cabinet nominees as he launches the new administration.

To “restore the soul” of the country, Biden said in his inaugural speech, requires “unity”.

“We can do great things, important things,” Biden said from the Capitol's west front. “We can make America once again a leading force of good in the world.”