PKR president-elect Anwar Ibrahim says there will be no cooperation between Pakatan Harapan and Umno, at least for now.

"Certainly not now, certainly not now. Nor have we considered this. They (Umno) were with PAS this morning at the conference," he told reporters in Singapore today, referring to Umno leaders attending PAS' 64th muktamar.

However, Anwar did not discount a tie-up in the future.

"Future case, que sera, sera (whatever will be, will be). But for now, it is certainly not in the equation," he said when asked about future possibilities.

Anwar's remarks come as Umno's Padang Rengas MP Nazri Abdul Aziz pledged to campaign for him in the Port Dickson by-election.

Nazri had said on Thursday that he wants Umno to work with PKR so the former ruling party can get back into government.

Meanwhile, Anwar also said he was unconcerned about allegations that Umno is exploring a merger with Bersatu.

"Why worry? They can approach any Pakatan coalition members. It is not a problem," he said.

Umno president Ahmad Zahid Hamidi confirmed earlier today that all party lawmakers had signed a statutory declaration empowering him to explore possible cooperations with all parties, including Harapan and PAS.

He did not discount working with Harapan parties despite Umno's recent leanings towards PAS, stating that the "door is open."