It is not unusual for a candidate's ties to special-interest groups to become a hot-button campaign issue, but when both candidates in a race are liberal Democrats in a deep blue state, and the issue is who is too close to unions, that deserves close attention.

At a debate last week between Los Angeles mayoral candidates, City Councilman Eric Garcetti accused opponent Wendy Greuel of being the "hand-picked" candidate of International Brotherhood of Electrical Workers Local 18, the union that represents 90 percent of the city's Department of Power and Water workers.

Greuel, the city controller, shot back that the charge was "pure hypocrisy," claiming that Garcetti had accepted donations from the union in the past and had even taken a "world class trip" at its expense.

The role of the IBEW Local 18 has been a running issue in the mayoral race, which is down to a May 21 runoff between Greuel and Garcetti. And it is hurting the controller, who is widely perceived as having the closer ties.

A recent Los Angeles Times poll gave Garcetti a 10-point lead over Geuel. "Voters named her as the candidate who cares more about unions representing city employees than Los Angeles as a whole," the Times wrote.

The situation is a telling sign that the tide is turning against public-sector unions. It is not just Republicans like Wisconsin Gov. Scott Walker taking them on, either. In Chicago, Mayor Rahm Emanuel is battling the teachers union. And now it is happening in the heart of California.

The reason is economics. The wages and benefits public-sector unions get in virtually all cases come from taxpayers. Many Angelenos think they are being ripped off by the public utilities, especially in the summer when air-conditioning bills soar.

For years, a major issue in L.A. politics was whether to appoint a "ratepayer advocate" to investigate the utilities. Garcetti pushed the idea but it was opposed by both the IBEW and Greuel, who argued that, as controller (i.e., chief auditor) she had that authority already.

Then Greuel and the IBEW lost that fight and the ratepayer advocate was adopted. He later produced a study that found Department of Power and Water employees received compensation 26 percent higher than similar workers at other facilities.

"That was bad for [the union leadership], but it didn't make Greuel look good, either. In all of her office's audits of the DWP, she had never made an issue of IBEW salaries," wrote the LA Weekly.

Not only that, but those wages put pressure on the city to raise wages for nonutility workers, too. Those soaring costs nearly bankrupted the city when the recession hit in 2008.

At last week's debate, Garcetti pushed the message home. "Now do you believe that there's zero dollars in fraud, waste and abuse at the DWP?" he asked. The audience groaned.

Why was Greuel asleep at the switch? The IBEW's chief lobbyist has visited her office 16 times in the past three years. That is "more access than just about anyone," the LA Weekly noted.

The lobbyist's wife is a fundraiser for Greuel. She even has a reminder for the lobbyist's birthday on her calendar.

When Garcetti raised questions in 2008 about a city solar energy project that would have benefited the union, Greuel reportedly insisted that the IBEW lobbyist would have to sign off on any changes.

IBEW has been watching out for Greuel, too, spending about $2.5 million so far to back her race.

A key problem with public-sector unions is that they don't just negotiate with the government, they are a constituent group for elected officials as well.

That can lead to the type of cozy arrangements like the one between Greuel and IBEW Local 18. Unfortunately for them, other voters in Los Angeles are becoming hip to this, too.

Sean Higgins ( shiggins@washingtonexaminer.com) is a senior editorial writer for The Washington Examiner. Follow him on Twitter at @seanghiggins.