My father is in a constant state of financial crisis and frequently turns to his children (my sister and me) for help. This has been going on for a long time, but has gotten worse since the passing of our mother in 2011. I am his eldest daughter the rest of us agree that I should help him manage. But he is stubborn and in denial and will not agree.
The suggestions I made were to allow your father to retain his self confidence, his sense of pride, and to give him an opportunity to let you help him without being obvious that he needs help. To "rub it in his face" is just cruel.
You can also imagine yourself in his place; how would you want your daughter or son to help you and allow you to still feel in control and maintain self respect?
Your father's made overtures to you for help; allow him to keep his dignity and accept that offer, graciously, and with sympathy and kindness.
Have a doctor evaluate his competency to deal with things and to see if he is depressed which he very well may be.
I'd talk with the doctor about your concerns ahead of time, but only tell him that the doctor wants to give him a check up.
I hope you already have medical and durable POA for him.
Even if you or someone else is not his medical POA, you can still voice your concerns to his doctor although he or she will not be free to discuss those concerns with you, but can be better informed about your dad's health. Elderly parents like to put on their very best for doctors in case you have not already noticed.
You might start with asking if he would like you to write checks and record them in the register (especially if his hands shake or his handwriting has deteriorated). Then you can ask if he would like you to HELP HIM balance the checking statement.
Other steps: would he like you to keep track of bills (date normally received so you know when to expect them, due date and dates paid) - that will give you a change to create your own schedule to help him monitor his finances.
I've been doing this for years, creating a duplicate check ledge and bill payment log so I know when bills are due and can pay them by phone if they manage to go off and hide someplace.
Don't even raise the issue of financial crisis or taking over. Make it seem as though you're just trying to be a helpful daughter.
If you can manage to get him to agree to add your name on his account, that will help you check it regularly to ensure that there's sufficient funds, etc.
With elders, I've found that often one of the biggest issues is wanting to donate in response to charitable solicitations with sob stories and pluck at a sympathetic person's heartstrings.