Nearly a decade ago, Albert Rivera caused a stir in Spanish local politics by posing nude in campaign posters. These days, he sports Hugo Boss suits but his campaign on the national stage is no less eye-catching: His upstart Ciudadanos Party is cutting into support for the ruling conservatives, threatening to bust open Spain's traditional two-party system.

Painful austerity has dented Spanish living standards, generating disillusionment with both Prime Minister Mariano Rajoy's Popular Party and its rival Socialists, which have alternated power since the fall of the Franco dictatorship in the 1970s. Voters are gravitating to renegades such as Rivera's business-friendly Ciudadanos, or Citizens, as well as the hard-left Podemos (We Can) Party, putting them virtually level in opinion polls with the traditional political heavyweights.

Rivera's party entered the national political race only five months ago — having until then been a key voice of Spanish unity in the independence-minded Catalonia region. But in this short time it has captured Spain's imagination with its brash talk that the political elite are a dinosaur-like class ripe for an electoral thrashing. By the end of the year, Rivera looks set to take on the role of political kingmaker.

"It's a new political era in Spain," Rivera told The Associated Press in an interview at the Catalan Parliament in Barcelona, where he serves as a lawmaker in between campaigning around Spain. "The latest opinion polls are giving a technical tie to the four parties and we'll see whether that's true or not. But at the very least, the political map is going to change substantially."

The first big test for Rivera and Citizens comes Sunday. That's when Spaniards angry about years of sky-high unemployment and seemingly never-ending government corruption cases elect leaders for 13 of the country's 17 autonomous regions, which function much like U.S. states. Spaniards will also vote for councilors in thousands of cities and towns.

Polls show Citizens getting 15-20 percent of the vote, roughly the same projected for the Popular Party, the Socialist Party and We Can, led by young, pony-tailed college professor Pablo Iglesias. The upcoming vote serves as the main test of voter sentiment ahead of a national general election that must be called by the end of the 2015.

Rivera readily admits Citizens would not count for much in this year's elections if nearly one-in-four Spaniards weren't jobless — despite steady Spanish economic growth over the last year — and revulsion wasn't spreading over a never-ending stream of sleaze.

In the latest scandal, Rajoy's Popular Party was hit hard last month when authorities raided the home and office of former IMF chief and Spanish economy minister Rodrigo Rato — a historic party figure — in a fraud and money-laundering investigation. Meanwhile, the Socialist Party is getting regularly slammed for two former party chairmen's alleged roles in siphoning money from public funds earmarked to boost employment and help hurting companies, while leading the southern region of Andalusia.

Voters born since Spain's return to democracy in 1978 are increasingly looking for alternatives — blaming the Socialists for failing to prevent Spain from entering into a deep economic crisis and the Popular Party for a recovery that has failed to generate jobs.

Citizens and Podemos — with their 30-something leaders — have rocketed in popularity as new political options. Polls suggest Citizens is mainly draining support from Rajoy's party while Podemos has taken it away from the Socialists.

"It's time for new faces in Spanish politics and Rivera is proof of that," said Antonio Barroso, an analyst with the London-based Teneo Intelligence political-risk consultancy. "You have a new player who is absorbing votes from these disenchanted voters and is business friendly."

Rivera was a national debating champion in college and helped found Citizens after gaining his doctorate in constitutional law. He spent years criticizing Catalan nationalism to a mainly local audience in Barcelona, until Citizens last year unexpectedly won two European parliamentary seats. That prompted it to declare in December that it would field candidates nationally for the first time.

The party scored a coup by signing up Luis Garicano, a respected Spanish economist and professor at the London School of Economics. Rivera and his team went on to build an organization and a political platform that advocates maintaining the country's social welfare system while cutting taxes, reducing red tape, investing in research and development and recruiting tech-savvy foreigners to start companies in Spain. Citizens also wants to create incentives to lure back well-educated Spaniards who left the country during the nation's 2008-2013 downturn.

The party also advocates controversial positions, such as eliminating local governments for towns with fewer than 5,000 residents by merging them with others, and halting expansion of Spain's popular bullet train system, the second most extensive after China's. While Citizens won't have a presence in all of the races that will be decided Sunday, it will field candidates in all 13 regional contests and in more than 1,000 Spanish municipalities.

Rivera has taken heat in Spain for refusing to characterize himself and his party as more to the right or to the left of center. He told the AP that Citizens is ideologically similar to Britain's Liberal Democrats — a progressive, pro-European party that is slightly left-of-center. The parallel may be a risky one: The Lib Dems surged in 2010 under the charismatic Nick Clegg, who became deputy prime minister in a coalition with the Conservatives, but lost most of its parliamentary seats this month in national elections.

Rivera emphasizes a pro-business ethos with a social conscience.

"You can believe in the ability and the strength of the individual, those building a business," Rivera said. "And at the same time I don't want there to be people in my country who can't get an education because they don't have money, or can't get health care or a pension."

And Rivera says that, while he has a John F. Kennedy-inspired commitment to public service, he is ready to give up his political career if the Citizens experiment doesn't work.

"If one day I have to choose between being happy and what I'm doing now," Rivera said, "I'll choose happiness."

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Associated Press writer Jorge Sainz contributed from Madrid.