The fifth phase of polling for the Lok Sabha elections is underway in 51 constituencies across 7 states. The fate of many eminent leaders including Congress president Rahul Gandhi, Sonia Gandhi, Home Minister Rajnath Singh hangs in balance as the voters shall be casting their mandate by exercising their franchise.

A total of 674 candidates are contesting in the phase five and nearly 8 crore 75 lakh people are eligible to vote in the seven states - Bihar, Jammu and Kashmir, Jharkhand, Madhya Pradesh, Rajasthan, Uttar Pradesh and West Bengal. Over 96 thousand polling booths have been set up in 51 constituencies.

Here are the key battles to look out for in phase five of national elections

Rajnath Singh Vs Poonam Mahajan Vs Acharya Pramod Krishnam - Lucknow

Home Minister Rajnath Singh is seeking a second term from Lucknow, a seat which BJP has been winning since 1991. Former Prime Minister Atal Bihari Vajpayee represented the constituency for five consecutive terms between 1991 and 2009. In 2009, Lalji Tandon, who is now the governor of Bihar, was elected to the Lok Sabha from Lucknow. Four-time Lok Sabha member Rajnath Singh, who won in 2004 from western Uttar Pradesh's Ghaziabad, took over the UP capital in 2014.

Rajnath Singh shall be locking horns against Mahagathbandan candidate Poonam Sinha, wife of actor-turned politician Shatrughan Sinha. Poonam Sinha, an actor herself, joined the Samajwadi Party last month nearly a week after her husband quit the BJP over differences with the senior leadership and joined the Congress.

Congress, which has gone solo in the general elections in UP, declared self-styled spiritual guru Acharya Pramod Krishnam as its candidate from the state capital, but that didn't stop Shatrughan Sinha from campaigning for his wife.

Rahul Gandhi Vs Smriti Irani - Amethi

The battle for the Amethi Lok Sabha seat between Congress president Rahul Gandhi and Smriti Irani is being considered the most high voltage clash in the fifth phase of polling. It is for the second time BJP's Smriti Irani is taking on Congress chief Rahul Gandhi in Amethi, a constituency that Mr Gandhi has been representing since the last 14 years.

Amethi has traditionally been a Congress stronghold where the party has lost only two Lok Sabha elections - in 1977 and 1998. In 1977, Janata Party candidate Ravindra Pratap Singh had defeated Sanjay Gandhi, son of then prime minister Indira Gandhi. BJP nominee and scion of Amethi royal estate Sanjay Singh defeated Congress candidate and former Union minister Captain Satish Sharma in 1998.

In 2014, Rahul Gandhi had defeated Union Minister Smriti Irani by a margin of over 1 lakh votes. Over the last five years, Smriti Irani has repeatedly tried to highlight Congress chief's neglect of the constituency. The BJP-ruled central government has launched several projects here like the assault rifle manufacturing unit for which the foundation stone was laid last month by PM Modi.

Besides Amethi, Rahul Gandhi is also contesting from Kerala's Wayanad. Mr Gandhi, who has been attacked by the BJP over contesting from two seats, said he decided to contest from south India to make a point that the voice of south was as "important" as rest of the country.

Sonia Gandhi Versus Dinesh Pratap Singh - Rae Bareli

Sonia Gandhi, the longest serving president of Congress, is seeking reelection from Raebareily for the fifth term. The BJP has fielded a former Congressman, Dinesh Singh Pratap, against the UPA chairperson on the seat she has held since 2004. The local strongman was elected to the state legislative council for the second time in 2016. He left the Congress last year.

Rajyavardhan Singh Rathore Vs Krishna Poonia - Jaipur Rural

It's a clash of two former Olympians in Jaipur Rural. Union Minister Rajyavardhan Singh Rathore, who won this Lok Sabha seat in 2014, has been again fielded by the BJP here. Challenging him is Congress candidate Krishna Poonia who won last year's Rajasthan assembly election from Sadulpur after a loss in the previous election.

On her contest against Mr Rathore, Krishna Poonia had said last month that "it is a fight to save democracy". "Our fight is not that of athletes. This is a fight to save democracy. There is a need to take up the issues of the youth, farmers and women," she told NDTV. "The BJP only makes promises.... When the nation's money was being looted, why were the chowkidars (watchmen) sleeping?" she had said. Krishna Poonia became the first Indian woman track-and-field athlete to win a gold medal at the 2010 Delhi Commonwealth Games.

Rajiv Pratap Rudy Versus Chandrika Roy

Former Union Minister Rajiv Pratap Rudy is BJP's candidate in Bihar's Saran, an RJD stronghold.

RJD chief Lalu Prasad Yadav won his first Lok Sabha election from Saran. He has represented the seat four times in the parliament. In 2014, his wife Rabri Devi lost the Lok Sabha seat to Mr Rudy, a close aide of veteran socialist leader and former Prime Minister Chandra Shekhar.

This time, the RJD has fielded ex-state minister Chandrika Rai. However, Tej Pratap Yadav, RJD chief's son, has been campaigning against his party urging people not to vote for Chandrika Rai, his father-in-law.

Rajiv Pratap Rudy had joined the BJP in the 1990s and after winning the now abolished Chhapra Lok Sabha seat in 1999, he was made a minister in the government headed by Atal Bihari Vajpayee. In 2014, he was among six union ministers asked to quit the Modi government after they were rated as under-performers in a review conducted by Prime Minister Narendra Modi and BJP president Amit Shah.