Joe Biden urged Georgia voters to surprise the nation once again by sending two Democrats to the US Senate, on the eve of a pair of critical runoff elections that will determine the balance of power in Washington and the scope of the president-elect’s ambitious legislative agenda. Biden, speaking at a drive-in rally in downtown Atlanta alongside Democratic candidates Jon Ossoff and the Rev Raphael Warnock on Monday afternoon, did not mention Donald Trump’s increasingly brazen efforts to overturn the results of the November election, which escalated this weekend when the president pressured Georgia’s secretary of state to “find” enough votes to reverse his defeat in the state. Instead, the he focused on what Democrats could accomplish with control of the Senate. “Georgia, the whole nation is looking to you,” he said, hours before Trump was due to take the stage at a rival rally for the Republican candidates in Dalton, Georgia, on Monday night. “Unlike any time in my career, one state can chart the course not just for the next four years but for the next generation.” If Democrats win both seats – no easy feat – the Senate would be evenly divided, with Kamala Harris, the vice-president-elect, serving as the tie-breaking vote. If Republicans win at least one of the races, Mitch McConnell will remain the Senate majority leader, making it far more difficult for the president-elect to deliver on top policy priorities such as healthcare, taxation and climate. Three million Georgia voters cast ballots during the early voting period, which ended Thursday – a record for runoff elections in the state. Nearly half a billion dollars has been spent on the twin races, as residents are bombarded with political ads and messaging urging them to vote in Tuesday’s elections. Biden and Trump’s dueling visits to the state on Monday highlight the urgency – and the stakes – of the contests, which will shape the political landscape for the first years of the incoming administration. Biden was the first Democratic presidential nominee in nearly three decades to win Georgia, where changing demographics, long-term voter mobilization efforts and a political realignment across the Atlanta suburbs have turned this once reliably Republican southern state into a presidential battleground. The state has certified Biden’s 11,779-vote victory in Georgia, but that hasn’t stopped Trump, who has refused to concede his defeat, from continuing to amplify false claims about the state’s election process and its results. On Monday, Biden thanked Georgia voters for electing him and joked that he had won the state “three times” because of the two statewide recounts. In an hour-long phone call to the Georgia secretary of state, Brad Raffensperger, on Saturday, Trump implored him to “find 11,780 votes” – just enough to reverse Biden’s victory in the state’s presidential election. A day after a recording of the conversation was made public, Gabriel Sterling, a top election official in Georgia, delivered a point-by-point denunciation of the meritless claims and debunked conspiracy theories cited by the president as evidence that the election was stolen from him. Alluding to Trump’s machinations in recent weeks, Biden said he would never demand loyalty from the state’s senators, who he said are elected to serve the people of Georgia and the constitution, not the president. “Politicians cannot assert, take or seize power,” he said. “Power is given, granted by the American people alone.” The tape has rattled Republicans in Georgia, who were already nervous that Trump’s fixation on his electoral loss could depress turnout among his supporters. During a rally in Georgia last month, Trump devoted considerably more time to airing his own political grievances with the state’s Republican leaders than promoting the Republican candidates he was there to campaign for. With control of the Senate at stake, the races have drawn firepower from some of the biggest names in politics. In a tweet on Monday, Barack Obama cast the runoffs as an opportunity to safeguard democratic institutions from an assault on American democracy. “We’re seeing how far some will go to retain power and threaten the fundamental principles of our democracy,” the former president wrote. “But our democracy isn’t about any individual, even a president – it’s about you.” Earlier on Monday, Mike Pence was in Milner, Georgia, to campaign on behalf of the Republican candidates, David Perdue and Kelly Loeffler. Speaking to supporters at a megachurch, the vice-president made no mention of the call between Trump and Raffensperger. Nor did he reconcile his support for an effort to reverse Trump’s defeat with his argument that Republicans need Perdue and Loeffler in the Senate to serve as a bulwark against the incoming Democratic administration. “We need Georgia to defend the majority,” he said, adding: “A Republican Senate majority could be our last line of defense.” Pence’s visit came a day after Harris held a drive-in rally with the Democratic candidates Ossoff and Warnock in Savannah. In her remarks, Harris assailed Trump for his call with Georgia’s secretary of state, calling it a “bald-faced, bold abuse of power” and “most certainly the voice of desperation”. Trump’s sustained assault on Georgia’s election system has further cleaved the party at the very moment they would benefit from unity. Since the November election, Trump has relentlessly attacked Georgia’s Republican leaders, who he has accused without evidence of ignoring instances of voter fraud. Last month, Trump called Georgia’s Republican governor, Brian Kemp, a “fool” and said he should resign. In Atlanta on Monday, Ossoff and Warnock seized the shared stage with Biden to galvanize their supporters one last time before polls opened on Tuesday morning for in-person voting. Warnock envisioned a “new Georgia” represented by “a young Jewish man, the son of an immigrant, and a Black preacher, the pastor of Ebenezer Baptist church, where Martin Luther King Jr used to serve and where John Lewis used to worship”. Osoff declared that Democrats were on the “cusp of a historic victory”.