Voters head to the polls on Tuesday to choose between two longtime fixtures of Los Angeles politics in a mayoral election shaped by the dire financial outlook of America's second-largest city and the political clout of its public employee unions.

City Councilman Eric Garcetti and Controller Wendy Greuel, both Democrats, advanced to the final stretch of their campaign after a flurry of weekend get-out-the-vote appearances in a race expected to draw one of the lowest turnouts in modern Los Angeles politics.

Garcetti, 42, and Greuel, 51, who is seeking to become the first woman elected Los Angeles mayor, emerged as the top two vote-getters in a non-partisan primary contest in March, setting up their head-to-head showdown on Tuesday.

A public opinion poll conducted last week by the University of Southern California and the Los Angeles Times found Garcetti leading Greuel, his former City Council ally, by 7 percentage points among likely voters, and by 6 percentage points among those who already had voted by mail.

However, the same poll showed Garcetti's lead narrowing since April and 11 percent of voters still undecided, while surveys earlier this month put the two in a statistical tie.

The winner will succeed two-term Mayor Anthony Villaraigosa as California's largest metropolis struggles to rebound from a sustained economic slump with a projected budget deficit set to top $1 billion cumulatively over the next four years.

Villaraigosa, who chaired the 2012 Democratic National Convention and ranks as one of the nation's highest-profile Latino politicians, is barred from running again by term limits.

The city's fiscal well-being has been crippled by dwindling tax collections wrought by the housing collapse and prolonged recession of recent years, along with rising public sector wages, pension obligations and other unfunded liabilities.

Both Garcetti and Greuel have vowed to slash city business taxes to help spur economic grown.

Both said they would seek to renegotiate a five-year, 25 percent pay increase they supported in 2007 for most of the city's 30,0000 municipal workers, a tack the city's powerful public employee unions are sure to resist.

LABOR POLITICS

The influence of organized labor became a key issue during the race, with Garcetti questioning Greuel's ability to wring concessions from public employee unions after they contributed heavily to her campaign.

To date, the police officers' union has given more than $1.4 million to groups supporting Greuel's candidacy, according to campaign records published by the city. The firefighters have spent nearly $500,000.

The union representing the powerful Department of Water and Power - the nation's largest municipal utility - has supported Greuel with about $2 million.

Greuel, who served as a deputy mayor under the late former Mayor Tom Bradley, has touted an endorsement from former President Bill Clinton, for whom she worked in the U.S. Housing and Urban Development Department.

Garcetti leads in campaign spending overall, with $9.4 million in expenditures, compared with $8.9 million for Greuel, according to City Ethics Commission figures. Much of that money has gone to a slew of negative television ads from both sides.

Garcetti has received backing from some smaller unions, along with white-collar sources such as real estate developers, businesses and Hollywood, a key constituency of his council district.

Garcetti touts his role in a reform passed by the City Council in 2012 that curbed wages and benefits for new hires, and increased existing pension and healthcare contributions.

Yet he not only backed wage hikes in 2007 but voted for big salary and benefit increases for Department of Water and Power workers in 2005 and 2009.

Known as a consensus builder, Garcetti served as council president from 2006 to 2011 and has called attention to his record on environmental initiatives and his role in the urban revival of once-blighted areas in Hollywood.

Greuel has touted her current role as a city controller in uncovering waste and fraud, while in her former council post she was known as the "Pothole Queen" for her dedication to street repairs in her suburban district.