The mood on Egypt's streets is turning ugly. At least 30 people were killed in riots in Port Said on Saturday, with a further three dying on Sunday at a mass funeral for the first victims. The protests followed the death sentences passed on 21 locals, all supporters of the Al-Masry football team for their part in the death of 74 police and rival Al-Ahly fans last February. The sentences, however appropriate they may seem for such a terrible crime, and however impartially the courts may have behaved in reaching them, are nevertheless being viewed by the people of Port Said as being ordered by President Mohamed Morsi. This after all is the way it would have happened under the dictatorial rule of Hosni Mubarak and Anwar Sadat before him. Hostility to the president and his Muslim Brotherhood government is rising like a whirlwind, once again, as with the revolution two years ago, sucking in disparate interests, even ardent football fans, and uniting them in a rising column of protest. This is, however, to ignore entirely the fact that Egyptians voted in their millions to choose their president and their parliament, even though the latter was ruled invalid by the courts and fresh elections must be held. It is there, at the ballot box, that the opposition must seek to win its arguments - not on the streets. The revolution was won in 2011. If further violence succeeds in forcing Morsi from office, then it will mean that after two years, all the achievements won with the blood and courage of so many Egyptians will have been for nothing. In effect the revolution will actually have been lost. Morsi may not have been wise in some of his decisions and may have failed to carry the greater part of the country with him, but this is not the excuse to try and force him from office. The president is trying to persuade 11 leading political groups to attend talks to see if national unity cannot be restored quickly. Some liberals are holding back demanding that concessions be made over the moderate Islamic constitution that was endorsed in last December's referendum. Morsi has declared a state of emergency in Port Said, Suez and Ismailia, and in the light of six days of running street battles in Cairo has said that he was prepared to take further steps to stop bloodshed. The talks he has called with opposition leaders are designed to head off this move. The opposition should attend without preconditions. If they do not, then nothing is going to stop the growing unrest and protests - nothing that is, except the army. And the clear danger has to be that if the army takes back the streets, the military will effectively take back the government because Morsi will become a president who is sustained in office by his generals. If opposition leaders refuse, then they have only one of two reasons. The most unacceptable is that some, at least, are trying to engineer the return of the armed forces. The alternative is that they are so intent on winning political battles in the streets rather than the ballot box, that whether they have the sense the realize it or not the revolution is in danger of being lost and all the sacrifices that were made by so many will have been for nothing.