A US pastor has sparked controversy after ending his prayer by saying "amen and a-woman".

Emanuel Cleaver, a Democrat Representative and pastor from Missouri, delivered the prayer at the opening of the 117th Congress and appeared to use his platform to support his party's recent push for gender-neutral language.

"May the lord lift up the light of his countenance upon us and give us peace — peace in our families, peace in this land and there I ask, oh Lord, peace even in this chamber," Cleaver said.

He closed with: "We ask it in the name of the monotheistic God, Brahma, and God known by many names by many different faiths. Amen and a-woman."

Republicans were not impressed by the prayer, with Rep. Guy Reschenthaler pointing out that amen is not a gendered word.

Reschenthaler erred in describing the word's origins as Latin as it is taken from Biblical Hebrew.

Cleaver's choice of words also caused confusion amongst other members of the clergy.

Cleaver has since defended his comments, saying they were meant as a tribute.

"I concluded with a lighthearted pun in recognition of the record number of women who will be representing the American people in Congress during this term as well as in recognition of the first female Chaplain of the House of Representatives whose service commenced this week," he said.

"I personally find these historic occasions to be blessings from God for which I am grateful."

Cleaver made his comments as other senior Democrats moved to do away with gender-specific references in Congress.

Nancy Pelosi, the Democratic Speaker of the House, announced the proposal as a "bold and future-focused" move, and said it would make the lower chamber of Congress the "most inclusive in history" for transgender and nonbinary people.

The move would do away with any gender-specific references, such as "man", "woman", "husband" or "wife" in the 45-page text of the rules that will govern the House during the 117th Congress.

Kevin McCarthy, the Republican leader in the House, wrote on Twitter: "This is stupid. Signed - A father, son, and brother".

Kelly Loeffler, a Republican senator standing for re-election in Georgia on Wednesday NZT, added: "The far-left's priorities, everyone. If you'd like to still be able to call yourself a father, daughter, mother or son, vote for me ... Sincerely, A Proud Daughter."

Democrats said the aim was to "ensure we are inclusive of all members and their families - including those who are non-binary".

References to "father" and "mother" would be replaced by "parent", while "son" and "daughter" would become "child".

Mentions of "brother" and "sister" would become "sibling". Aunts and uncles would be changed to "parent's sibling".

Other changes would include altering "submit his or her resignation" to "resigns", "chairman" becoming "chair", and "seaman" being changed to "seafarer".

The proposal was put forward by the Democrat-led House rules committee, which is sometimes known as the "traffic cop of the House", and backed by Pelosi.

- Additional reporting, AP