Pitched fighting intensified Monday in Yemen’s second-largest city, Aden, leaving streets littered with bodies as Shiite rebels and their allies made their strongest push yet to seize control of the main bastion of supporters of the country’s embattled president.

The fierce fighting in the Arabian Sea port raises doubts about a plan to land ground forces from a Saudi-led coalition backing President Abed Rabbo Mansour Hadi to try to carve out an enclave for Hadi, who flled the country two weeks ago.

Saudi Arabia has asked Pakistan to contribute soldiers to the military campaign, as well as air and naval assets, Pakistan’s defense minister said Monday. Pakistan’s parliament is debating the request and is expected to vote in coming days.

The Saudis have been leading an air campaign since March 26 against the Houthis and their allies, military units loyal to Hadi’s predecessor, ousted autocrat Ali Abdullah Saleh. On Monday, Houthi fighters and pro-Saleh forces attacked Aden’s Moalla neighborhood, one of the last districts held by Hadi loyalists, where the presidential palace, port facilities, TV, government offices and a military camp are located.

“We are jumping over dead bodies,” said Radwan Allawi, a pro-Hadi fighter.“It’s intense street fighting, direct fire.”

Coalition forces started an airdrop of weapons to Hadi’s forces on Friday, but some military officials say the weapons are falling into the wrong hands.

The number of casualties was not immediately known, with medical facilities in the city overwhelmed and volunteers coming under fire from rival groups.

Military experts say the intense fighting makes any ground operation in Aden far more difficult, particularly if the administrative center falls.

If Aden falls, ground forces “would be deprived of that location, which can be a command center,” said retired Yemeni army general Khairi Hassan. He said coalition troops might still attempt to land at a smaller coastal town west of Aden, but at greater risk because there are few supportive forces there.

Mustafa al-Ani, a security analyst with close ties to the Saudi government, said a large-scale ground operation is “out of the question,” though a small number of special forces could be sent to guide airstrikes and gather intelligence.

“You don’t have the solid ground, the safe haven, where you can land your troops,” he said of Aden.

Instead, the aim of the air campaign is “to break the back” of the Houthis and force them into negotiations, while encouraging Sunni tribes to revolt against them, said al-Ani, a Dubai-based analyst for the Gulf Research Center.

The Sunni-majority Saudis and other Gulf Arab sheikdoms are alarmed at what they charge is the insurgency backed by Shiite Iran in a country that borders Saudi Arabia and occupies a strategic position that could be sued to block access by oil tankers to the Suez Canal.