How do I tactfully tell my daughter and nieces that they need to visit their grandfather more often?

I think a lot of people are freaked out by the sick and dying. They have absolutely no practice at it and it's overwhelming. The sight, the smells, the awkward silence. The anticipatory fear "something" might happen and I'll either look a fool or be in the way.

I think the awkward feeling scares a lot of potential visitors away. Nobody wants to feel like an incompetent visitor.

Tell them EXACTLY what is OK for a visit, such as: You only need to be there about 10 minutes. Grandpa is fine with us just sitting there with him in the room. He can't be part of the conversation, but he is aware of us being there. We can talk to each other about anything and it's good for him. Or Grandpa is OK with us just sitting in the room not talking. We don't have to be in an active conversation with him or about him. Your presence is what is good for him. It's OK if there are long periods of silence.

I've said it before & I'll say it again - we've lost the ancient art of the visit. This used to be common practice on Sundays after lunch. Drive around, see who might be home, and "sit a spell" with them. It was not considered an intrusion unless it lasted a long time. People also had to know how long was polite and then to get up & leave before then.

I can't imagine how irritated I would be nowdays if somebody showed up on my doorstep to just sit & take up my time on a Sunday of all days. I'm busy!

Forget tact, you need to come right out and ask for what you need. And be specific. If you need a couple of hours respite, or help with laundry, or shopping done say so, that way there are no misunderstandings. Say "grandpa really misses you, what day can you be here?" Avoid vague language that lets them weasel out with promises of someday.
And as pamstegman says, you can't expect all of them to be good at caregiving, but each of them should be able to figure out how to contribute something.

You have had a contentious relationship with your father. What kind of relationship did the grandkids have with him? Time is running out. You see this as an urgent last chance, but prepare for the possibility that they are not interested in a last chance. For them, perhaps that boat has sailed.

If you have a good relationship with them, I think your appeal should be as a help to you. (Although I don't really see how getting them to visit helps you. If you think it does, that is the basis for your appeal.)

I say you don't. It should not become his grandkids burden to take care of him. Hire some help and let the grandkids remain grandkids.

I am with cwillie. I do not understand nor forgive relatives who get so reluctant at this pressing time.

I think sometimes it is a matter of age and that some younger people are very uncomfortable with the whole getting older and dying thing. I've heard some younger people even say things like why go, they were never that much of a part of my life which tells me that they did not have much of a connection. Other younger people are more comfortable with being around a wider range of people like my youngest son and have not problem with visiting elderly grandparents. My oldest son is not as comfortable with visiting elderly grandparents or older people in general. His personality is more selective than his younger brother. While you can ask them to come and visit, you can't really make them if they are now grown adults on their own.

Sometimes you have to be a little urgent in your tone of request. The other issue is whether or not they are any good at caregiving. My SIL will visit her mother, but she is totally useless as a caregiver. Her brother asked her to give mom a shower and she said "WHAT?!?!?!" and managed to avoid doing it.
So brother went to the head nurse, who got it done. SIL will not check her legs, take her BP/O2/temp nothing, nada, no go. How she managed to raise two kids is a total mystery.

All helpful answers. I really don't expect them to find time to do anything other than visit him. Worse is that today we found out that his previously treated cancer has metastasized. Chemo may or may not be an option. But it does bring to light that time is fleeting. I find myself feeling very cheated by powers-that-be, I've put so much into this, mentally and financially. My boss has been super at easing my schedule, but that has only made me more dependent on Dad. Tonight I'm just a hollow mess (yes, I know that makes no sense, but I can't describe it any other way).

Then your efforts at getting those nieces and nephews going is all the more urgent. You have to "use" the "Time Is Running Out" approach. Best wishes for success, and I hope they do realize what they will be missing, if they don't respond appropriately.

Thanks zookeeper. I've been passing the news on the the family today. Being snowed in today was a blessing. I spoke with my Mum who is my rock. (She and Dad have been divorced over 40 years, they get along pretty well). Then I wrote the details out in emails for my brothers who both live far away. i just calaled my daughter (31) and asked her to call her cousin who lives near her and I'm going to call my oldest neice (36) and ask her to convey the information to my other niece (27 and pregnant) and tell her. My nieces lost their Mom (my sister) five years ago to pancreatic cancer and then just about 2 months ago, their father died of a sudden heart attack. I really hate the idea of piling more sad/bad news on, but it won't keep. So I am now forced into being straight forward with telling them that they need to visit as much as they can. I pray that the time will be more years. I lost my own husband to cancer almost 23 years ago to cancer, and then lost an ex-boyfriend that I had lived with for over 7 years and stayed very close with to ALS. For someone that's bi-polar and suffering from the PTSD from the losses I've had, I'm trying very hard to keep it together. Today's a bad day, Tomorrow will be better. (I'll keep saying that until I am livingit.)