Venezuelan President Nicolas Maduro is returning to Caracas after a 10-day international trip, having secured billions of dollars in foreign investments to help his cash-strapped country but no success in halting the fall in global oil prices. But Maduro will be coming home to bigger problems: Discontent over widespread shortages has ballooned in his absence, threatening to bring back the mass protests that roiled the country last year.

Lines at Venezuelan supermarkets have swelled in recent weeks as customers waited for hours to buy food and basic household items. Venezuela is notorious for its frequent shortages, but the current crisis has hit a new level. Authorities in some states began banning customers from lining up at night, and others have restricted shoppers from buying groceries on certain days. In some areas, police have guarded markets to prevent protests from breaking out.

“The shortages are worse now than they had been in many years,” David Smilde, a senior fellow at the Washington Office on Latin America, said by phone from Venezuela. Even more worrying for Maduro’s government, he said, was that the crisis was now affecting Venezuela’s poor, who have traditionally made up the government’s main support base.

Outcry over rampant shortages, as well as high crime rates and the government’s economic policies, led to mass protests in February that posed the biggest threat yet to Maduro’s administration. The demonstrations lasted more than two months and led to more than 40 deaths of protesters and security forces. They eventually faded as opposition groups fractured and the protests failed to garner visible support from the poor. But Smilde said current tensions are putting Venezuela back on the brink of that chaos again.

“All it would take is some kind of high-profile violence and we would have a repeat of protests from last year,” he said.

Small protests already have cropped up in the western city of San Cristobal, the epicenter of last year’s demonstrations. Meanwhile, opposition leaders, including former presidential candidate Henrique Capriles, have called on Venezuelans to take to the streets en masse again next week.

Venezuela’s economy has been in dire straits, particularly as the price of oil, which makes up 96 percent of the country’s exports, plunged by about 50 percent in the second half of 2014. Predictions of default also have abounded as the Moody’s ratings agency downgraded Venezuela’s rating this week to Caaa-3, citing a “negative” outlook for the country. Maduro’s international tour, which included trips to China, Qatar, Saudi Arabia, Iran, Algeria and Russia, was widely seen as a bid to secure financial assistance to help the country weather the storm. Speaking from Moscow Thursday, the president hailed his trip as a success.

“We have obtained the necessary resources for the country to maintain its pace of investments, imports and economic stability,” he told reporters. During his trip, Maduro announced a $20 billion investment deal with China as well as “several billion dollars” of financing from Qatari banks, all going to unspecified projects in energy, agricultural and social development. But critics said he failed to secure direct loans that would have provided more immediate relief for the economy.

Meanwhile, Maduro’s larger aim -- lobbying members of the Organization of the Petroleum Exporting Countries to reverse the downward trajectory of oil prices -- proved unsuccessful. The energy minister of the United Arab Emirates reaffirmed this week that OPEC would not cut oil production to boost prices. Analysts estimate Venezuela needs prices to rise to $120 a barrel to stay afloat, while Venezuelan officials have pushed for prices closer to $100 a barrel. Crude has traded below $50 a barrel most of this month.

Maduro’s popularity has slumped over the past year, with his approval rating at 22 percent in December, according to polling firm Datanalisis. Smilde said the president’s eroding support would make it even harder for him to push through needed changes. “The government’s facing a really bad situation because they have to carry out some reforms like devaluation and raising the gas price, and they have very little political capital to do it,” he said.

Members of the opposition have blamed Venezuela’s problems on the government’s economic model rather than the oil price crash. During a press conference in Caracas this week, Capriles called on Venezuelans to send a message to the government through next week’s planned demonstrations: “To the followers of [late President Hugo] Chavez, I say this with respect: This revolution has ended.”