English to Spanish Social Sciences Idioms / Maxims / Sayings

I have decided to compile a somewhat thorough English-Spanish glossary, a long-standing goal I have had for many years but never actually done. In approximately 10% of the cases, I am recurring to you, my colleagues on Proz, to ask you to help me get appropriate translations into Spanish of a number of idioms.

I want to assure everyone that ALL TRANSLATIONS WILL BE SHARED on the open forum we have in Proz. The way I guarantee this is by choosing “one answer” to which I incorporate many of the other answers, and then I click to save the question and answer on the open Proz forum.

Selection criteria: 1) extensive usage throughout the Spanish-speaking world. I am counting on your help, and since usually colleagues simply agree without adding where they know the translated term to be used, I am not able to specify this in the answers. This is not a commercial enterprise, but rather an informal exercise for the benefit of all of us. 2) Many times there are really creative idioms that are used which, although not used necessarily through the Spanish-speaking world, would be readily understood by all. I am particularly happy to include these in the open forum so that we can all enjoy them in our use, whether literally, or perhaps with an adaptation to the degree that each translator deems appropriate for that particular target population.
Please, when you agree with an answer, mention the countries in which you know such idiom to be used, if not already mentioned by another colleague. Since this project is so time-consuming and endless, and since, like you, I have such a heavy load of translations and interpreting jobs to do and cannot spend umpteen million hours on it, I must count on your help. And although simply listing countries because another translator says so is in no way scientific, at least it is an interesting start.

Finally, I know context is everything. Quite often I will give the meaning(s) in which I am interested, and I will attempt to include a sample. Some sources, such as the Random House Dictionary, already have an example, so there is no need for me to do this, since time is of essence.

Thank you for your help.

Definition: be in the strongest or most advantageous position

example:

David Alistair Yalof, a University of Connecticut professor who wrote "Pursuit of Justices," said that real consultation on Supreme Court picks has generally occurred when a president was weak or had higher priorities. "None of the circumstances that typically produced real input are present here," he said. "Ultimately, the president holds all the cards, and the president knows that."

Democrats know that, too, which is why they are trying to put down markers on consultation. But Leahy said they hold one important card, as well. "I have no problem with the fact that the final choice is the president's and the president's alone," he said. "But the final choice of consenting is ours alone."