думаю, что он придет на вечеринку,

думаю, что он придет на вечеринку, но давай позвоним ему на всякий случай.

Results (English) 1:

I think that it will come to the party, but let's call him just in case.

Results (English) 2:

I think that he will come to the party, but let's call him just in case.

Results (English) 3:

I think that he will come to the party, but let's позвоним him just in case.