Kenyan police tightened security in the capital, Nairobi, as senators debated contentious amendments to the nation’s electoral laws ahead of a presidential vote next year.

The Senate is discussing changes approved by the National Assembly last week that allow for alternatives to biometric voter identification and the manual transmission of poll results. The Coalition for Reforms and Democracy, Kenya’s main political opposition group, says the amendments may enable the ruling party to rig the ballot.

The speaker directed the chairman of National security to investigate under what circumstances police came to parliament.

“This is not a police state. We are a democratic country,” the speaker said.

The legislators were meeting to consider controversial changes made to the electoral laws as adopted by the National Assembly on December 21.

CORD, led by former Prime Minister Raila Odinga, staged protests last week in Nairobi as lawmakers voted on the amendments. It’s planning more demonstrations from Jan. 4 if President Uhuru Kenyatta signs the changes into law.

The Senate hearing on the proposed changes will continue on Jan. 4, when the views of the chamber’s legal affairs committee will be heard, Senate Speaker Ekwee Ethuro said in remarks broadcast on KTN News, a closely held Kenyan broadcaster.

Kenya’s Independent Electoral and Boundaries Commission has proposed including provisions for the manual registration of voters, bypassing a planned biometric system, according to Odinga. Such a system could enable the names of dead people to be included on the voters’ roll, he said.