it is difficult to say vs it becomes difficult to say

Some examples from the web:

• From that moment it is difficult to say what and how our fellow sisters went through in those terrible years of war here.
• For this reason it is difficult to say if a language can be considered not necessary because it was not spoken.
• On the other hand, it is difficult to say what is an adequate level of liquidity and money supply under normal circumstances.
• Very often European Union Member States are only a link in the chain - a product may be manufactured here from raw materials obtained in a third country, so it is difficult to say who the true manufacturer is.
• The development of this idea into architectural form passed through a compositional process in which it is difficult to say if the mathematical structure precedes or proceeds from the architectural image.
• It is difficult to say where a line can be drawn between the Community method and the inter-state method in foreign policy, and Mr Rehn, the new Commissioner, admitted as much during his hearing before the Committee on Foreign Affairs.
• André Breton was basically the one who held up the Surrealist movement, so it is difficult to say that he belonged to any of the two groups.
• They are fostering enterprise and promoting business but it is difficult to say how many businesses they are helping and how successful that help is.
• In fact, it is difficult to say exactly what the threat is - and that is part of the problem.
• Whether this means he is cautious or that it takes time to figure out the whole picture, it is difficult to say.
• And besides, it is difficult to say where the study ends and the actual painting begins. I am considering a few worked out pieces [...] like figures against the light of a window, for instance (489; 396).
• Mr President, in the EU, matters are so often on the agenda that it is difficult to say when the various developments begin.
• The auditors state that the accounts are fair but fail to state that they are true, and indeed it is difficult to say they are true if they go on to express concern about the quality of the financial information.
• It is difficult to say how much the Commission has spent on e-learning.
• It is difficult to say which vehicle is more beautiful.
• It is difficult to say which of the three has been worst.
• It is difficult to say how free the election will be.
• It is difficult to say whether the Appeals Chamber judges were aware of such implications.
• It is difficult to say which one is better.
• It is difficult to say why you make some choices.

Some examples from the web:

• It becomes very difficult, not to say impossible, therefore.
• Increased sweating, it becomes difficult to transfer heat.
• When it is agitated, it becomes difficult to see.
• For them it becomes difficult to give an answer.
• When it is low, it becomes difficult to drive the.
• It becomes difficult to aim while standing up.
• It becomes difficult to know the right time of ovulation, especially when your periods are irregular.
• It becomes difficult to pause and recover depth in life.
• When it is agitated it becomes difficult to see.
• Speaking of practical initiatives that contribute to peace in the world, one could then expand upon some specific case, even though it becomes difficult to choose.
• Mechanisms often so complex that it becomes difficult to understand, or even simply to describe them.
• It is equally easy to settle in Italy as in Greece, it becomes difficult to support themselves and their family.
• When we look at the large variety of coffee mugs, it becomes difficult to select the right one.
• IOS is so ahead, while keeping things simple, that it becomes difficult to explain all its advantages.
• If the declaration on religious freedom is anti Sillabo, it becomes difficult to speak about continuity.
• It becomes difficult to convince even a small number of people to join such an organization and start the process of growth.
• Otherwise, it becomes difficult to return to. Projects vary, so from the technical point of view, fundamental steps can change.
• When workers are employed as casual labour, it becomes difficult to provide them with proper training on the health and safety protection standards to be observed.
• But the site's gradual appeal to hackers and it after sometime it becomes difficult to monitor the site.
• As a Church we insist on this, while many of our parliaments acrossEuroperecognizes other types of families, and so it becomes difficult to influence legislators to defend family values.