Bugis-style roofs curve majestically over swanky Shah Alam Club, where the who's who of Malaysia's richest state Selangor gather poolside for a view of its capital below. But, just next door to the private members' club, a housing estate sits abandoned and derelict, its brick fences disintegrating to reveal lawns overgrown with weeds.

Such examples of uneven development litter the state, which both gains and suffers from its proximity to bustling centre Kuala Lumpur and administrative capital Putrajaya. Selangor surrounds these two federal territories, and many of its six million residents work in the two cities and pay the higher prices that come with them.

"The poor are being urbanised," Umno's deputy Selangor chief Mat Nadzari Ahmad Dahlan told The Straits Times. He claims the mushrooming of construction sites - something that has turned most of the state into urban or suburban townships - has not come with "new promises of economic development and people have no opportunity to make a good living".

The two federal territories come under the central government, led by ruling party Umno, while Selangor state is controlled by opposition pact Pakatan Harapan, headed by Parti Keadilan Rakyat (PKR).

With cost-of-living issues at the forefront of most voters' minds, both sides are now vying to show how they can better manage Selangor and improve the lives of the state's residents.

Money problems Mr Zulfadzli Halim, a 34-year-old aeronautical engineer, said the RM8,000 (S$2,600) he and his wife earn each month is barely sufficient for their expenses.

"I can barely manage," said the father of four. "You can give your children food, clothes and shelter but if you don't have excess money to invest in their education, it is not good enough. It's really tough," he said, while eating with his family at a rundown foodcourt within sight of the sparkling new Melawati Mall, which opened in July.

Income inequality and high costs form the common grouse of suburban voters, particularly in Selangor.

While the state has the highest household income in the country - bar the two capitals - it is also the most expensive state to live in, according to the latest income and expenditure surveys in 2014.

Official statistics show that, from 2009 to 2014, household expenses in Selangor grew by an average of 11.1 per cent annually to RM4,646 monthly, but incomes grew by only 6.7 per cent to RM8,252 monthly.

Selangor's income growth is also well below the national average of 8.8 per cent, while its increase in household expenses is the second fastest among all states.

A bidding war Admittedly, many of the economic policies that affect the average citizen - a new goods and services tax, lower petrol subsidies, cash handouts for the needy - are set by the central government, which means voters are less likely to blame the state government for their economic predicament.

"The opposition has shown they can manage taxpayers' money. Even though it's tough to make ends meet, at least it's very unlikely Harapan will raise taxes or tariffs on me," said Mr Zulfadzli.

Still, state governments have wide powers to encourage business activity, via decisions on land use, water supply, business permits, quit rent and other local regulations.

State-government sources told The Straits Times that Selangor Menteri Besar Azmin Ali recently went overseas to market Selangor to foreign investors. Welfare programmes will be the main campaign plank for Harapan, they said, notably the state's RM2 billion Inisiatif Peduli Rakyat, or Caring For The People Initiative, which gives aid for water supply, housing and business loans.

Umno, meanwhile, hopes to charm voters with its hefty federal budget - from which state grants can be made - and big-ticket plans.

Batang Kali assemblyman Datuk Mat Nadzari said "it would be a waste" if voters did not recognise the benefits of having the same party in charge of the federal government also administering Selangor.

Prime Minister Najib Razak has already kicked off a concerted campaign to win back Selangor, repeating the mantra of integration with Kuala Lumpur's development.

To drive home the point, in July he launched a new MRT system which traverses the capital before terminating in the Selangor township of Kajang.

Barisan smells blood

Voter welfare, however, is not the only factor spurring the battle for Selangor.

From Barisan's perspective, out of the three states in Malaysia it does not control, Selangor is its best bet for conquest. This is despite Barisan winning just 12 of 56 seats in the state legislative, and five of 22 parliamentary wards in the 2013 elections.

Barisan is eyeing a further 31 state seats, 21 of which were marginal areas that were won by opposition candidates - including chief minister Azmin Ali - with only 57.3 per cent of the vote or less.

Also, the departure of Parti Islam SeMalaysia (PAS) from the opposition coalition, and its threat to contest against its former allies at the next election, could split support for the opposition and hand advantage to Barisan.

Selangor would also be a major scalp for Barisan president Datuk Seri Najib, who has faced an internal revolt since graft allegations surfaced in 2015.

Observers say the Premier has set his sights on winning back the affluent state, and regaining a two-thirds parliamentary supermajority ceded in 2008, to finally silence dissent within his own party and entrench his authority.

Three-cornered fights notwithstanding, voters' economic woes may still impede Barisan's progress.

Election strategist Ong Kian Ming, from Harapan's strongest component Democratic Action Party, said voting patterns in Selangor over the past three decades show that the state is the most sensitive to economic trends, with support for Barisan spiking in 1995 and 2004, when the good times rolled, but plunging after financial crises at the 1999 and 2008 polls.

"A large number of the more than two million voters... are not originally from Selangor. Many of them moved to Selangor because of better job and educational opportunities," the Serdang MP said.