The Tory leader used Question Time to reverse his party's previous opposition to the use of ground troops for any task other than to police a peace settlement.
To Labour jeers, Mr Hague insisted he had always supported the Government's aims of "getting the Serbs out of Kosovo and getting the refugees home".
Earlier this week the Tories were accused of breaking the consensus after Michael Howard, opposition foreign affairs spokesman, condemned the bombing of the Chinese embassy in Belgrade as a "gross act of incompetence".
Mr Howard also said the impression was being gained that "the military action is being made up as we go along and has not properly been thought through".
But yesterday Mr Hague stressed Nato's action must be "seen through to success". He said the damage done so far to President Slobodan Milosevic's military capacity was "testimony to the professionalism of the allied forces".
But, he added: "The chief of the defence staff, General Sir Charles Guthrie, said yesterday that Nato's air assault had not stopped the killings.
"Nato, despite all our hopes for the air strikes, may soon confront a difficult choice - either to accept a compromise which you have rightly said before you would regard a failure or to pursue a different military course that will achieve these objectives.
"Can you assure us that General Guthrie and his fellow officers in Nato have the men, equipment and freedom of action to pursue a strategy that they believe will succeed?"
Replying, Tony Blair made clear the campaign would carry on and, if necessary, intensify. He was well aware of the effects of the Balkan winter on a land campaign and said the alliance would plan for "all contingencies".
"It's true that the humanitarian suffering has been enormous. But that makes me all the more determined to reverse this policy of ethnic cleansing and to allow these refugees back home.
"As far as I'm concerned, there will be no compromise on Nato's demands. There must be no compromise. It's not simply a question of defeating this policy of ethnic cleansing, or a question of Nato's credibility.
"But if we allow, right in the heart of Europe, a policy effectively of racial genocide to succeed, we will pay the price of it for many years to come."
Mr Hague said timing remained a concern. "We are concerned that the air campaign has not succeeded so far, that preparation has not always been adequate and time may be running out. If we wish to assemble and deploy troops to allow the refugees to return home before the winter, Nato needs to make any decision on ground troops in the very near future."Reuse content