Joe Biden returns to campaign trail

(CNN) - Many of the Democratic presidential candidates spent the long weekend campaigning hard, with one notable exception: Joe Biden.

The former vice president hasn't made a public appearance since his kickoff rally in Philadelphia 10 days ago.

That streak ends Tuesday in Houston.

Democratic rivals ran in parades or appeared at other events, but Biden spent Memorial Day weekend off the campaign trail.

His official campaign guidance read, "Joe Biden has no public events scheduled."

After a three-week burst through the early nominating states, Biden currently is running a frontrunner's campaign. It's lighter on public appearances and heavy on raising cash.

"I promise you this, no one, no one is going to work longer, no one is going to campaign harder to win your hearts, your trust, and your support," Biden said.

In all, Biden has mingled nearly as much with voters as he has with donors, holding nine fundraisers and 11 public events since he entered the 2020 race one month ago.

In the last week, he attended three fundraisers in Tennessee and Florida, with no public appearances. He was seen meeting with staff at his campaign offices in Washington, D.C.

"There's much more we need to do to build a middle class," Biden said. "And in the coming weeks, I'm going to go into a great deal more detail about this."

Biden's next month is expected to focus on mapping out policy, including this week with events in Houston and Dallas homing in on education.

And in his third run for the White House, he is likely to spend a large portion of his time preparing for that first debate one month away.

"I'm anxious to be able to stand before people and say what I think and why I'm doing what I'm doing," he said.

Thus far, Biden has avoided tangling with his Democratic opponents, keeping his focus squarely on President Donald Trump.

"President Trump inherited an economy from the Obama/Biden administration that was given to him, just like he inherited everything else in his life," Biden said. "And just like everything else he's been given in his life, he is in the process of squandering that, as well."

Two weeks ago in New Hampshire, Biden promised he'd give a speech on climate change by the end of the month. So far, his campaign hasn't confirmed a date or location for that speech.

Copyright 2019 CNN. All rights reserved.