Liverpool had an offer accepted for the 24-year-old on Monday but face strong competition from Chelsea.
Pompey executive chairman Peter Storrie said: “The matter will come to a conclusion at the beginning of next week. I do not have a preference over the move, it is up to Glen.
“The deals are almost identical so it really is down to him and what club he prefers, which one is going to pay him more money.
“Glen wants to play regularly in the Champions League, he has got himself back in the England side so I understand that. Sometimes you have to be fair to players.”