However, Antonio Barroso, a London-based analyst with Teneo Intelligence political and business risk firm, said he didn't expect the election to "crucially affect" the government's room for maneuver.
"It could have been much worse" for the Social Democrats, he said, and "the Socialist Party could have done much better" given the widespread hardship.
The Social Democrats govern with the smaller Popular Party.
The absence of a broad political consensus on how to restore the country's fiscal health has hurt Portugal on international financial markets. In a sign that investors are jittery, creditors have recently driven higher the interest rate Portugal pays on its loans.
Fears also have grown that Portugal, which is supposed to resume borrowing money on the open market in the middle of next year after correcting its public finances, may need a second bailout.
Despite two years of austerity policies, the government has repeatedly missed deficit reduction targets. The three major international ratings agencies still classify Portugal's credit worthiness at junk status.
Prime Minister Pedro Passos Coelho made no immediate comment, but he has previously vowed to press ahead with the bailout program even if his party performed poorly Sunday.
Socialist spokesman Miguel Laranjeiro said his party "is the big winner on this election night, and the Social Democrats are the big loser."
The government has to lop another 3.6 billion euros ($4.9 billion) off the state budget next year, when the retirement age will increase to 66 from 65. That is likely to bring more strikes and street protests.