My key is difficult to turn the ibnition to start engine

First check the battery is fully charged. Diesel engines take a lot of effort to crank over so need a full battery charge to start correctly.
Has the vehicle been difficult to start recently? A clicking noise usually means the starter motor has failed. Power is getting to it but it is refusing to turn. You will most likely need to replace it with a new one.

Ch eck all ur fuse s and relays sounds likd ur startef or ibnition fuse / relay there are both for both of them shoulf be likd 2 to 3 fuses for ur ignition alone google , ..... fuse box diagram underhood ......for your year make model and size engine ..
Match ur fuse box with one to it because it will show u all different ones if all fuses and relays are good uou will know the fuses will be in same location as urs ...... then google year make model ect. Starter relay location.... its one or other fuse or relay to one of them

Egr has nothing to do with your vehicle turning over hard.connections, battery, and starter are what you want to look at.

The battery needs to be replaced. After the first start in the morning the battery gets charged and the engine is also "hot" making it easier for the starter motor to turn it over. Therefor less current is drawn from the battery and you get a start every time. In the morning the engine is cold making it difficult to turn. The battery rested the night loosing some charge and is also cold which affects the current it can deliver at that stage. With the cold engine it is not able to turn it fast enough to get it started. A new battery will solve your problem.

Check to see if there is any loose connections but it could be the starter is going out

sounds like you need to replace the ibnition

the reason it's starting after a few turns of the key is because when you're the ignition position, you're priming the engine to start. By priming it repeatedly, you're making it easier on the starter to catch when you finally try to turn the engine. I would first check the spark plugs and electrical wiring.

if it runs smooth, it's probably a fuel pressure regulator. If it runs rough, you may have a bad injector that is leaking when the car is off.

What car , and year and engine? What color smoke?

Try putting turning pressure on the steering wheel both right and then left as you are trying to turn on the switch. Some times the steering lock will put pressure on the switch, making it difficult to turn switch on.