Low-polling billionaire presidential candidates Mike Bloomberg and Tom Steyer have spent a collective $200m on political advertising in the 2020 election race – with the first state votes for the Democratic nomination still six weeks away.

Of the two, the financial data mogul Bloomberg is firmly ahead, with the former New York mayor spending a record $120m since he formally joined the contest.

The San Francisco billionaire Steyer hasn’t matched Bloomberg with his campaign’s $83m in ad buys, but that is still more than four times Pete Buttigieg’s $19m, the next big spender.

Put together the $200m spend is more than double the spending of the rest of the entire Democratic field this year.

But the larger question for the billionaire duo is whether their ability to spend so much on media advertising is effective; both remain in the single digits among registered Democrats nationally.

And as the 2016 primary and national contests showed, deep pockets only go so far; Jeb Bush and Hillary Clinton’s impressive financial backing proved no match for the current president’s cost-free, direct-to-voter Twitter assaults.

Still, according to a Quinnipiac poll, Steyer’s spending in South Carolina is beginning to slowly move the polls: he is now placed fifth with 5% of projected Democratic voters. And he is at 4% among black voters – ahead of Buttigieg and Cory Booker.

Bloomberg, too, is starting to see modest polling gains. In the latest Quinnipiac national poll published on Monday, he came in fifth nationally with 7% of the vote.

Steyer, however, is at 1.5% nationally, according to RealClearPolitics.

But Bloomberg and Steyer are running fundamentally different campaigns with a common objective. Steyer is spending heavily in early voting states – Iowa, New Hampshire, South Carolina and Nevada – while Bloomberg is hoping to harvest support in delegate-heavy, Super Tuesday states.

Tom Steyer speaks in the spin room following a Democratic presidential primary debate in Westerville, Ohio. Photograph: John Minchillo/AP

According to Politico, Bloomberg has already spent more than $13m in California, with 416 delegates, Texas, with 228 delegates, and Florida, which carries 219 delegates.

The former New York mayor isn’t stopping there: he’s spending across the nation, even in states like New Hampshire, with just 24 delegates, which he is not contesting. Other states that are receiving massive TV advertising include North Carolina, according to data from TV ad-tracking firm Advertising Analytics.

“We’re running out of ways to describe [the ad expenditures] at this point,” the company’s Nick Stapleton told Politico.

But others warned that an overplayed ad brings in diminishing returns.

“After you see the same TV ad 10 times, it’s not going to have as big an impact,” Saber Communications’ Christian Heiens told the site, pointing to Jeb Bush’s $55m ad spend on his 2016 Republican nomination bid.

Saturation spending can also lead to mistakes. On Tuesday, the Bloomberg campaign acknowledged and apologized for “unknowingly” using prison labor to make voter calls on his campaign’s behalf.

The issue was reported by the Intercept, and confirmed by Bloomberg in a statement.

“We do not support this practice and we are making sure our vendors more properly vet their subcontractors moving forward,” he said.

But with a personal fortune of $54bn and beholden to no donors, Bloomberg aide Howard Wolfson made clear in a November interview with the Associated Press that his boss is willing to spend “whatever it takes to defeat Donald Trump”.

Notwithstanding his own bid, the liberal-leaning, 77-year-old former Republican plans to spend $15m to $20m on voter registration programs targeting half a million underrepresented, Democratic-leaning people in the battleground states of Arizona, Michigan, North Carolina, Texas and Wisconsin.

“One of the arguments that we would make on behalf of Mike to primary voters is [that] he is able to wage these two campaigns simultaneously – effectively and simultaneously,” Wolfson said.