HARRISBURG — Candidates for Pennsylvania’s Supreme Court have spent heavily on air-time bookings for campaign TV ads — about $1.5 million as of one week before Tuesday’s primary election, according to two national groups that analyzed Federal Communications Commission filings.

Washington-based Justice at Stake and New York University Law School’s Brennan Center for Justice said Wednesday seven of the 12 candidates have purchased air time in what is likely to be the most expensive judicial campaign in state history.

The final tally for TV spending in this year’s campaign could surpass the record $4.6 million in 2007, when two seats on the high court were open.

An unprecedented three seats are open this year on the seven-member court, the state’s highest.

Two of the vacancies resulted from resignations of former justices implicated in scandals. The groups said half of the ads aired so far focused on the need for ethical or court reforms.

“Given the court’s history with scandal, it’s no wonder the candidates are spending big on ads that focus on ethics,” said Alicia Bannon, counsel at the Brennan center.

Among the Democrats, Philadelphia Judge Kevin Dougherty spent at least $686,000 on TV contracts, Superior Court Judge David Wecht spent at least $221,000, Superior Court Judge Anne Lazarus committed at least $138,000 and Jefferson County Judge John Foradora put up $118,000, the groups said.

Republicans spent less. Superior Court Judge Judy Olson and Adams County Judge Mike George jointly booked ad contracts worth at least $128,000 in addition to separate contracts of at least $71,000 for George and at least $15,000 for Olson. Judge Anne Covey booked contracts worth at least $76,000.

Not buying air time as of Tuesday were Democrats Christine Donohue, a Superior Court judge, and Allegheny County Judge Dwayne Woodruff; and Republicans Correale Stevens, an appointed Supreme Court justice, Superior Court Judge Cheryl Allen and Montour County District Attorney Rebecca Warren.

Collectively, the candidates had raised nearly $5 million as of Monday, the closeout date of their last full campaign finance reports before the primary.

Pennsylvanians for Modern Courts, a Philadelphia-based judicial reform group, has advocated for years elections for appellate judges should be replaced with a merit selection process in which a panel would evaluate and recommend candidates.