The countdown has begun for the first phase of polling. Among the key constituencies that are going to polls in the first phase are Nagpur in Maharashtra, Jamui in Bihar, Ghaziabad, Muzaffarnagar, Saharanpur and Gautam Buddha Nagar in Uttar Pradesh.\u00a0Three Union minister are in the fray in the first phase - Nitin Gadkari, VK Singh, and Mahesh Sharma. We take a look at how these ministers fared in the last Lok Sabha elections and their challengers in the upcoming polls. Nagpur In Nagpur, Congress candidate Nanabhau Patole is challenging senior BJP leader and Union Minister Nitin Gadkari, who had won this seat by over 2,80,000 votes in 2014. Gadkari has a proven track record when it comes to delivering on promises and it will be difficult for Patole to defeat Gadkari on his turf. In the last elections, Gadkari had defeated Congress candidate Vilas Muttemwar. The BJP leader had won 54 per cent of the vote share, while Congress leader had to settle with just 28 per cent. Jamui Sitting MP and LJP leader Chirag Paswan is contesting from Jamui. Even though nine candidates are in the fray, the main contest will be between Paswan and RLSP candidate Bhudeo Choudhary. In 2014, Paswan had defeated RJD candidate Sudhansu Kumar Bhaskar by over 86,000 votes. Paswan had got 2,85,352 votes, while Bhaskar could secure just 1,99,407 votes. This time, the candidate who is challenging Paswan is from the Upendra Kushwaha-led RLSP \u2014 which was earlier with the NDA but snapped its ties over seat-sharing differences. The RLSP is now part of the grand alliance in Bihar. Ghaziabad The BJP has re-nominated its sitting MP VK Singh from Ghaziabad constituency, where he defeated Raj Babbar by over 5 lakh votes in 2014. Singh got over 56 per cent vote share and Babbar could secure just 14 per cent. The BSP and SP secured the third and fourth spots with 12.89 per cent and 7.97 per cent respectively. But this time, the SP and BSP have come together and fielded only one candidate. Going by the previous numbers, if the alliance succeeds in consolidating its vote share, then it will be in a position to put up a tough challenge to the BJP. The SP has fielded Suresh Bansal, while Congress's Dolly Sharma will take on VK Singh. Muzaffarnagar Here, sitting BJP MP Sanjeev Kumar Balyan will face RLD chief Chaudhary Ajit Singh. In the last Lok Sabha polls, Balyan had defeated BSP leader Kadir Rana by over 4 lakh votes. The BJP MP had got close to 59 per cent vote, while BSP and SP received 22.77 per cent and 14.52 per cent respectively. However, the scenario has changed this time with just one candidate taking on Balyan as the grand alliance candidate. The SP and BSP have not fielded a candidate, which is expected to help Ajit Singh against the BJP. In 2009, RLD candidate Anuradha Chaudhary had secured 34 per cent vote share but was defeated by Kadir Rana. But it shows that RLD has a presence in this constituency and if Ajit Singh succeeds in repeating that performance then results could be different this time. Saharanpur Saharanpur is set to witness a triangular contest with Congress and SP-BSP alliance challenging sitting BJP MP Raghav Lakhanpal. In 2014, Lakhanpal had defeated Congress candidate Imran Masood by over 65,000 votes. Lakhanpal got 4,72,999 votes and Masood settled with 4,07,909. The BJP got over 39 per cent vote share, while the Congress secured 34 per cent. The BSP came in third with 19.67 per cent vote, while SP could get just 4 per cent. The Congress once again has fielded the controversial Imran Masood to take on BJP's candidate Lakhanpal. From the grand alliance, BSP has fielded Haji Fazalur Rahman in Saharanpur. Gautam Buddha Nagar Here, the contest will be between grand alliance candidate Satbir Nagar and sitting BJP MP and minister Mahesh Sharma. In the last election, Sharma had defeated SP candidate Narendra Bhati by over 2,80,000 votes. The BJP got 50 per cent vote share, while SP secured 26.64 and BSP 16.63 per cent. This time, the road for the BJP minister may not be easy if SP and BSP perform a little better than what they did in 2014. The two parties had together received over 43 per cent vote share, six per cent less than the winning candidate. However, Mayawati and Akhilesh Yadav have one problem as the Congress could eat away some of the votes from the grand alliance.