ABUJA (Reuters) – Nigeria’s lower house of parliament voted on Thursday in favor of constitutional amendments to reduce the presidency’s powers, the latest step in a power struggle between President Muhammadu Buhari and the national legislature.

The Senate, parliament’s upper house, led the way on Wednesday in backing constitutional changes that could weaken the presidency and boost the legislature, prompting a senior official in Buhari’s government to speak of “a very unhealthy” power grab.

Senate head Bukola Saraki, who has been tipped as a possible successor to the ailing Buhari and who is pushing the changes, said on Wednesday they would help boost Nigeria’s political, economic and social development.

Though the House of Representatives broadly accepted the major proposed amendments, it rejected some that had been passed by the Senate.

The two chambers will now form committees to meet and agree on a final version of the proposals before sending them to state assemblies.

The amendments must still be approved by two thirds of those 36 regional state parliaments and then be signed off by the president.

The measures include providing certain legal immunity to members of the legislature and reducing the president’s ability to withhold assent for a bill passed by parliament.

The parliament also voted to impose time limits on key presidential decisions such as nominating ministers and proposing federal budgets, both of which have been much-delayed under Buhari.

Buhari, 74, is currently in Britain where he has spent much of the year receiving treatment for an undisclosed medical problem.