UK parliament honors murdered MP Jo Cox

In a rare display of unity on Monday, members of the UK parliament returned to the House of Commons for a special sitting - allowing lawmakers to honor their late colleague. The 41-year-old Labour MP was shot and stabbed on a street in Birstall, West Yorkshire, on Thursday.

In a break with tradition, members were also allowed to sit together, rather than dividing along party lines.

Prime Minister David Cameron urged lawmakers to join forces against "the hatred that killed her."

Following Cox's murder last week, several commentators in the UK questioned whether the tone of the political debate over the EU referendum had contributed to the MP's death.

Taking a stance against the tactics used by the "Brexit" campaign, former Conservative Party chair and "Vote Leave" advocate Baroness Sayeeda Warsi announced on Monday that she was defecting to the "Vote Remain" camp.

Warsi accused the Brexit campaigners of peddling hate and xenophobia to fuel their cause, drowning out moderate voices in the process.

"This kind of nudge-nudge, wink-wink xenophobic racist campaign may be politically savvy or politically useful in the short term, but it causes long-term damage to communities," she told the BBC.

Cox's alleged killer, Thomas Mair, was due at Central London Criminal Court later Monday for a bail hearing. When asked to give his name at his first court appearance on Saturday, the 52-year-old replied: "Death to traitors, freedom for Britain."

Three days until EU referendum

The special parliamentary sitting on Monday comes just three days before the UK heads to the polls to vote on the country's membership in the EU.

According to an average of polls calculated by research site What UK Thinks, support for the "remain" campaign increased over the weekend, leaving both camps with exactly 50 percent support.

British bookmaker Betfair also said the probability of the UK voting to remain in the EU has risen by 7 percent since Friday to 72 percent.

'No going back'

In a final bid to lay out their case to voters, politicians from both the "remain" and the "leave" camps flogged their campaigns on Monday.

Pro-Brexit campaigner and former London Mayor Boris Johnson told readers of The Daily Telegraph that they could "change the whole course of European history."

"I hope you will vote leave, and take back control of this great country's destiny," he said, adding: "This chance will not come again in our lifetimes."

Arriving for a meeting with EU counterparts in Luxembourg on Monday, British Foreign Secretary Philip Hammond warned the electorate, however, that a vote to leave the EU would be "irreversible."

"There will be no going back," Hammond said.

Cameron and Corbyn face live TV audiences

In a televised appearance on the BBC on Sunday, British Prime Minister David Cameron also called on the UK to vote "remain."

"If we do leave we are walking out the door, we are quitting," Cameron urged. "I don't think Britain at the end is a quitter. I think we stay and fight. That is what we should do."

The prime minister was due to speak again at a "remain" campaign event later on Monday, while opposition Labour leader Jeremy Corbyn was also due to be grilled by a live television audience as he makes his case for "remain."

With the vote still too close to call, other EU member states continued to urge the UK on Monday to remain in the EU.

German Foreign Minister Frank-Walter Steinmeier told Germany's RND media organization that a "Brexit" would be "a great shame for the European project," warning that the UK's departure could turn around decades of the integration of the 28 member states.

"In Europe we share the responsibility to not fall back into the nationalism of individual states," Steinmeier said, warning of the growing support for right-wing populism across the EU.