It’s the nation’s most expensive Senate race. We dig into where Fetterman’s and Oz’s money comes from.

The fund-raising in Pennsylvania’s competitive and hugely expensive Senate race has been a study in contrasts.

Democrat John Fetterman has relied on a steady stream of small-dollar donations: While raising $48.5 million, nearly half has come in increments of $50 or less. Meanwhile, about a quarter of Republican Mehmet Oz’s $13 million raised has come from donations that small. Oz’s fund-raising has been fueled by his own fortune and larger donors pouring money into his campaign.

Oz last week added $1 million more of his own money to his campaign, bringing his personal spending on the race to more than $22 million.

Still, recent disclosures show some shifts in the campaign’s final months as both national and Pennsylvania donors have invested heavily in a race that could decide control of the Senate.

Oz’s small contributions have grown significantly from August, a sign of a stepped-up fund-raising effort and, perhaps, grassroots Republicans coming around to a nominee who had been left bruised in the primary.

Fetterman, meanwhile, has seen a continued spike in national support, his latest fund-raising disclosures show. While about half of Fetterman’s campaign money came from out-of-state donations when he won the Democratic nomination in the May 17 primary, it’s now closer to 63%.

(There is one caveat: About 20% of Fetterman’s donations can’t be categorized because they weren’t made electronically and are so small that the campaign is not required to disclose specific donor information about them.)

The bump in national support is probably to be expected: Once the lieutenant governor won his party’s nomination in May, he became the Democratic standard-bearer in one of this year’s most important Senate races. Democratic donors from other states might not have had a strong preference for which Pennsylvanian won the state’s primary, but they’d be motivated to back any nominee against the GOP.

Oz has seen a somewhat opposite trend. After relying mostly on his own money and large donations from out-of-state allies during the GOP primary, he has seen his share of Pennsylvania donations tick upward.

Again, that’s also fairly expected. After a fractious Republican primary contest, it was likely Pennsylvania Republicans would eventually begin chipping in to help whoever won their nomination.

Pennsylvania’s Senate race, including the primary and general election, and counting spending by candidates and outside groups, has been the most expensive in the country, totaling nearly $290 million, according to the nonpartisan group OpenSecrets.

Still, despite the opposite recent trends, overall Fetterman has raised far more money in Pennsylvania ($9.5 million as of Sept. 30) than Oz ($3 million).

Fetterman has now raised 37% of his campaign dollars from Pennsylvanians, down from about 49% as of May 17, the date of the primary.

Oz has raised 27% of his campaign funds from Pennsylvania donors, up from about 22.5% on primary day. At that time Florida — where Oz owns a mansion — narrowly accounted for the biggest share of his donations. Now it’s second.

Fetterman says his in-state support, and the many small donations from everyday people, reflected his Pennsylvania roots and grassroots backing.