The Long War Journal reports the Mahdi Army is taking a hit in Baghdad:
Clashes between the Mahdi Army and US and Iraqi forces continued in Baghdad over the weekend as efforts to complete the security barriers separating the southern portion of Sadr City from the Mahdi Army-controlled north. The US military has moved another battalion of Strykers into the Sadr City.
US and Iraqi forces have killed 18 Mahdi Army fighters in Sadr City and New Baghdad since the afternoon of May 3. Nine Mahdi Army fighters were killed in Sadr City and northern and eastern Baghdad during the nighttime and early morning hours of May 4-5 after attacking US forces, planting roadside bombs, or preparing to launch mortars and rockets.
US soldiers killed four more Mahdi Army fighters in the eastern district of New Baghdad after coming under attack on May 4. And US troops killed five more Mahdi Army fighters in Sadr City as they attempted to stop the barrier from being built late May 3 and early May 4. No US soldiers were reported killed in any of the incidents.
Sadr City has long been the stronghold of the Mahdi Army and they're fighting hard to keep it, as illustrated by these two other articles at The Long War Journal...
Sadr City barrier 'a magnet' for Mahdi Army attacks
US troops kill 28 Mahdi fighters in Sadr City
... as well as these statistics.
US and Iraqi forces have inflicted heavy casualties on the Mahdi Army in Sadr City and surrounding neighborhoods since the fighting broke out in Baghdad on March 25. According to US and Iraqi reports compiled by The Long War Journal, 502 Mahdi Army fighters have been killed in and around Sadr City.
Meanwhile, Muqtada al Sadr is believed to be in Iran.