Iraqi women running for parliament this month are undaunted, despite many challenges they face ahead of the May 12 elections - including unprecedented smear campaigns complete with sex videos that forced some to withdraw from the race.

Many see the vote as a chance to push women's issues to the fore in this traditionally male-dominated society, where women still find it hard to win a powerful place in politics.

There are legitimate concerns that women's rights are being eroded, 15 years after the U.S.-led invasion toppled dictator Saddam Hussein with hopes of bringing democracy to a nation long staggering under wars, oppression and countless economic and social problems.

Nearly 2,600 female candidates are vying for a quarter - a quota allotted to women under the constitution - of parliament's 329 seats in these elections, the fourth since Saddam's 2003 ouster.

Fatin Rasheed Hameed, a candidate with the Baghdad Alliance party dominated by the country's minority Sunnis, says the smear campaigns are "unacceptable."

Iraqi women account for 57 percent of Iraq's population of over 37 million, according to the U.N. Development Program, and despite government efforts to address gender inequality, the situation for Iraqi women has declined steadily since 2003.

According to the UNDP, one in every 10 Iraqi households is headed by a widow. In recent years, Iraqi women suffered further economic, social and political marginalization due to decades of wars, conflict, violence and sanctions.

In the 1950s, Iraq had a liberal society, becoming the first Arab country to name a female minister and adopt progressive laws for women and the family. But, the situation started to decline during Saddam's era and became further complicated after 2003, mainly due to the rise of the country's religious institutions but also militancy and extremism.

In 2014, Islamic State militants seized human rights lawyer Samira Salih al-Nuaimi when she was at home with her husband and three children in the northern city of Mosul.

The extremists tortured and then publicly killed her after their self-proclaimed religious court ruled that she had abandoned Islam.

Those harrowing images may still haunt Iraqi women ahead of the elections - the first since U.S.-backed Iraqi forces defeated IS, declaring earlier this year that the war against the Islamic State group had been won.

In the streets of Baghdad and elsewhere, posters of women candidates have been plastered on electricity poles and buildings, alongside those of men.

Some depict veil-framed faces while others show candidates with make-up and without the traditional Islamic headscarf, or hijab.

Both provoked a harsh response - many posters were splattered with mud, defaced with beards drawn on or completely torn up.

For the first time, harassment and smear campaigns against women running for a seat in parliament moved online.

Sex videos have been widely circulated on social media purporting to show female candidates in bed with men, as well as photos allegedly showing candidates posing in underwear or revealing outfits.

One such video - which she dismissed as a "fabrication aimed at pushing her out" - forced Intidhar Ahmed Jassim, allied with Prime Minister Haider al-Abadi's Victory Alliance party, to withdraw from the race.

In Iraq's southern Najaf province, tribal arbitration was held over a video showing a young man kissing the poster of a female candidate from another tribe.

The outcome: he apologized, the apology was accepted and the female candidate's tribe even declined compensation for the insult.

Alarmed by the unseen level of harassment, the U.N. chief's special representative for Iraq, Jan Kubis met last month with several women candidates over the "alarming situation" and "vulgar acts" targeting women, which he said only undermines the democratic process.

Baydaa Salim al-Najar, who was at the meeting, said the attacks "systemically target candidates without the hijab, to knock you down."

She is one of 45 candidates from Iraq's minority Yazidis - an ethnic group particularly targeted by IS in horrific attacks. Al-Najar accused Iraq's dominant parties of being behind the harassment of women - mainly as a campaign against new faces.

The Baghdad-based lawyer is making her priority to raise the voice of Yazidis, especially Yazidi women, many of whom were enslaved by IS militants in their self-proclaimed caliphate. Sunni extremists consider non-Muslims infidels who deserve to be killed.

For Iman al-Safi, who runs on the Wisdom party list, the smear campaign will spur women on to stand up for their rights and fulfil their dreams.

"Women constitute half of society and they raise the other half," she said. "We will achieve what we are striving for."