Joe Biden's campaign — which is grappling with weakening poll numbers, a disappointing third-quarter fundraising haul and attacks from President Donald Trump over Ukraine ties — rallied its leading donors and fundraisers over the weekend in Philadelphia as it looks to reestablish momentum in the race for the Democratic presidential nomination.

That means increased emphasis on Super Tuesday primaries March 3, when 40% of delegates are up for grabs, and not necessarily on the earliest nominating states, Iowa and New Hampshire, where campaigns usually seek to grab an early toehold in presidential races.

According to attendees who spoke on condition of anonymity due to the private nature of the talks, senior campaign officials told leading Biden fundraisers, or bundlers, that the campaign is looking to boost the number of its fundraising events and bolster its online donor program in a bid to dominate Super Tuesday. California, North Carolina and Texas all hold their primaries that day.

The weekend sessions, which were scheduled before the most recent developments in the polls and the Ukraine scandal, were held at the 201 Hotel. They were led by campaign manager Greg Schultz, deputy campaign manager Pete Kavanaugh and other leaders.

"They need to raise a substantial amount. Super Tuesday comes immediately after the first four states," said a business executive helping Biden raise cash and who participated in the strategy session. When asked how the aides described their upcoming efforts, this person said: "More events with him, surrogates, and ramping up online. They feel good about ramping up online."

Attendees described the senior campaign officials' remarks as a "rah rah speech" — and a call to beef up fundraising efforts in order to have the best chance at picking up delegates in earlier primary states such as Nevada and South Carolina. These primaries are scheduled for February, after the Iowa caucuses and the New Hampshire primary. In the most recent surveys, Biden is ahead of the pack in Nevada and South Carolina but slightly behind in Iowa and New Hampshire.

"Goal for 4Q [fourth quarter] was, 'Let's ramp it up with traditional events, and let's beef up the online contributions,'" said another backer of Biden's who took part in the meeting. "I agree timing is an issue — we need enough to get through Iowa and New Hampshire. Staying in the hunt through those two and crushing them in S.C. will bring in the Super Tuesday money. So we need to do reasonably well in those two."

Former Pennsylvania Gov. Ed Rendell, who attended the gathering and is helping Biden raise campaign cash, brushed off donor concerns about polls and fundraising.

"Donors are always worried. I've never had donors that are 100% confident," Rendell told CNBC on Monday. "If the polls show that they you are winning by 20, they ask why aren't you winning by 23."

These discussions came just days after the Biden campaign announced an underwhelming third-quarter fundraising haul of slightly more than $15 million. The former vice president's tally for the period was less than the takes for Sens. Bernie Sanders and Elizabeth Warren and South Bend, Indiana, Mayor Pete Buttigieg.

Biden's front-runner position has weakened substantially. He is virtually tied or slightly behind Warren in some surveys, and his once-massive lead over Warren in the Real Clear Politics polling average has collapsed to 0.3%.

A Biden campaign spokesman declined to comment.

Biden recently spoke about his possible path to victory through the electoral college at a fundraiser in California. The former vice president mentioned the state of North Carolina as one he thinks they could win while noting Texas could be a long shot.

"I think we can win Georgia. And I think we can win North Carolina," he said last week. He labeled the Lone Star state, along with later primaries in Georgia and Arizona, as "a stretch," while noting, "I don't want to jinx myself."

Georgia holds its primary March 17, and Arizona's is March 24.

Politico recently reported that Biden's campaign plans to increase its staffing in Super Tuesday states.

Still, Biden's campaign privately stressed that in order to make inroads, it needs to efficiently raise the cash necessary to compete, and possibly win, the majority of the Super Tuesday delegates. Biden's campaign said the last week of the third quarter represented its best seven days of online fundraising since May.

While the campaign gave the impression to donors that it may spend more online, Biden's political organization has seen a dip in Facebook ad spending over the past 30 days. The social media giant's ad library shows the campaign has spent over $280,000 on Facebook ads since Sept. 5, which was less invested than other primary contenders over that same time period, such as Warren, Sanders, Buttigieg, Sen. Kamala Harris and billionaire Tom Steyer. Facebook is often used by campaigns to appeal to grassroots donors and help bring in small donations.

Biden himself spoke to more than 100 financiers at the weekend event — and signaled that he's going to ratchet up his attacks on Trump in the Ukraine scandal, donors said. The president has repeatedly linked Biden and his son Hunter to unproven claims of corruption in Ukraine.

Trump himself is embroiled in an impeachment inquiry by the House of Representatives after a whistleblower alleged the president asked Ukraine's president to investigate the Biden family. While Trump has denied wrongdoing, he recently said China should also look the younger Biden's business ties there while reiterating his call for Ukraine to investigate.

Biden wrote an op-ed for The Washington Post, which was published over the weekend, in which he forcefully pushed back on Trump's attacks.

"And to Trump and those who facilitate his abuses of power, and all the special interests funding his attacks against me: Please know that I'm not going anywhere," Biden wrote. "You won't destroy me, and you won't destroy my family. And come November 2020, I intend to beat you like a drum."

Biden also recently put out a new attack ad against Trump titled "Unhinged" as part of a $6 million media effort in the early states. CNN reports the ad will run in Iowa, New Hampshire, South Carolina and Nevada as a digital spot and will be broadcast on a few of those television markets.