A motion to refer nine more parliamentarians to the High Court over possible dual citizenship has failed.

Key points: Documents show Gallagher applied to renounce British citizenship before electoral nominations closed last year

Documents show Gallagher applied to renounce British citizenship before electoral nominations closed last year But confirmation of renunciation did not come back to her until August 16, two months after closing date

But confirmation of renunciation did not come back to her until August 16, two months after closing date Labor argues she took all reasonable steps to renounce, but have asked High Court to decide

But the House of Representatives has referred ALP backbencher David Feeney to the High Court to test his eligibility.

Labor and the crossbench all voted for a motion to send four Labor MPs including Mr Feeney, four Coalition MPs and crossbencher Rebekha Sharkie, to the High Court.

The Coalition opposed the motion and the result was a 73-all tie.

Speaker Tony Smith had to exercise his casting vote on the motion and followed the usual practice which was to vote.

While the Speaker's action meant the vote did not succeed, Labor Manager of Opposition business Tony Burke said it was "completely consistent" with how casting votes had been made in the past.

After that motion failed, Mr Burke moved the motion to refer Mr Feeney because he cannot find the paperwork to show he renounced British citizenship.

If the High Court rules he was ineligible because he was a dual citizen, there would be a by-election for the marginal inner-Melbourne seat of Batman that Mr Feeney holds.

Earlier on Wednesday, Labor leader Bill Shorten refused to endorse Mr Feeney as Labor's candidate for the seat if a by-election was called.

Mr Shorten said he did not want to pre-empt the High Court.

Labor Senator Katy Gallagher was referred to the High Court earlier on Wednesday.

Senator Gallagher's documents show she was still a dual British citizen when nominations closed for last year's election.

But Labor has argued she should not be found ineligible because she took all reasonable steps possible and the British Home Office took 118 days to process her renunciation.

Senator Gallagher emphasised in the Senate that she has legal advice that she is eligible.

She said the Coalition has tried to attack her eligibility and reputation and she wanted the matter resolved, which is why she asked for it to be sent to the High Court.

But the tied vote on the referral motion in the House of Representatives means other Labor MPs facing citizenship questions will not be considered by the High Court at the moment.

Labor backbenchers Justine Keay, Susan Lamb and Josh Wilson all appear to have been dual British citizens at the close of nominations last year.

The Labor motion was also to send Liberal MPs Julia Banks, Nola Marino, Jason Falinski and Alex Hawke and as well as crossbencher Ms Sharkie, but as it has failed it is not clear how the questions over their eligibility will be answered.

Sorry, this video has expired Bill Shorten refuses to say whether Opposition will refer Labor MPs to High Court over citizenship

Turnbull asks why Labor MPs weren't referred before

The Government's leader in the House of Representatives, Christopher Pyne, described the day's events as deeply disappointing.

"The Government wants to debate marriage equality, the Government wants to get on with that — Labor doesn't. Labor wants to debate politics as they have done all week," Mr Pyne said.

"It is still the Government's view that [those MPs it named as questionable] should be referred to the High Court."

He said the Government would not be striking a deal with Labor that involved referring any of its own MPs to the High Court.

"No, we won't be doing that. There are no people in the Coalition partyroom that have doubt over their citizenship at all," Mr Pyne said.

As Labor argued its MPs had taken all reasonable steps to get rid of their dual citizenship, constitutional law expert Anne Twomey said it would be up to the High Court to rule on the issue.

"So the question that needs to be resolved is whether it is enough to have done everything that the candidate can do before the nomination date; so sending off your renunciation, paying the fee, filling out the forms," Professor Twomey said.

"If the test is that as long as you've done your part, that's enough, they should all be fine."

But Professor Twomey said the High Court had recently taken a much more narrow view of the so-called reasonable steps test.

"Just referring to it in relation to circumstances where, otherwise, the other country wouldn't accept renunciation at all," she said.

"Now if that is the view, taking a much stricter line on it, then these people are in trouble."