Mr Biden’s Democratic campaign announced on Tuesday a $15 million (£11.85 million) week-long TV, radio and print advertising campaign in six states: Arizona, Florida, Michigan, North Carolina, Pennsylvania and Wisconsin.
President Donald Trump won all six states four years ago. The television purchases, which involve ads in English and Spanish, also extend to national cable television, including Major League Baseball’s Opening Day broadcasts.
Separately, the campaign is using top surrogates in the coming days for virtual events targeting a number of cities, including Las Vegas and Milwaukee.
The headliners include two women mentioned as potential running mates: Illinois Senator Tammy Duckworth and California Senator Kamala Harris.
While the moves underscore Mr Biden’s wide-ranging approach, they also highlight lingering questions about spreading the campaign too thin.
Four years ago, Democrat Hillary Clinton’s presidential campaign made a show of expanding its efforts into GOP strongholds like Arizona and Georgia, while the candidate herself spent no time in Wisconsin and little time in Michigan or Pennsylvania – states her campaign viewed as reliably Democratic.
President Donald Trump ended up sweeping all those states.
We’re not trying to get to 400 electoral votes, but we’re trying to have as many paths as possible to the 270 that it takes to win
“We’re not trying to get to 400 electoral votes,” Mr Biden’s deputy campaign manager Kate Bedingfield told The Associated Press in a recent interview.
“But we’re trying to have as many paths as possible to the 270 that it takes to win.”
The presumptive Democratic nominee still has not reserved television advertising for the fall.
Mr Trump’s Republican reelection campaign has reserved more than $146 million (£115.34 million) already.
Mr Biden’s campaign manager, Jen O’Malley Dillon, and other aides have pointed to the campaign’s uptick in fundraising to assert that they can build a wide playing field without being spread too thin.
The campaign and the Democratic National Committee have outraised Mr Trump for the last two months but still trail the GOP’s combined accounts in cash on hand.