1. Here in the United States, the most important and powerful labor unions are those of people who work for the government (teachers, police officers, office workers, etc.). 2. Other labor unions used to (formerly) be very powerful. But -- as you know -- many industries have left the United States and gone to other countries. So there are fewer workers (making automobiles, for example) and with fewer workers comes less power. 3. Yes, labor unions may strike. But in this bad economic situation, many labor unions realize that maybe it is not a good idea. For example, the workers at one company recently struck. What happened? The owners closed the business. Now the workers are unemployed. 4. Yes, the labor unions are very important in elections. As I explained, the government employee unions are the most powerful. They have lots of money (collected from members). If they like candidate X, they will spend money for TV commercials and they will walk door to door in order to remind people to vote for candidate X. 5. Most Americans do NOT belong to labor unions anymore. The unions are trying to get new members. For example, the unions are recruiting people who work in hotels, etc.

we have but not like your i heard labor union in china is so hard.

In Canada labor unions have the right to strike. The Garbage men/women have done it before, and teachers have gone on strike. So I know it can happen. I do not know what you mean by political issues. Often individuals voice their own personal political concerns. However, there is nothing stopping unions from being involved politically. I cannot think of any examples right now, but I'm sure its happened. Why do you ask?