Frenchman Jean Van de Velde, who led after Round 1 was completed earlier on Friday, stands at 8-under-par 134 after a 1-under 70. He was joined there by Jonathan Lomas (69) and Soren Hansen (69). Francois Delamontagne and Martin Erlandsson are one stroke further back at minus-7.
The first round was completed early Friday after being suspended for the night Thursday due to lightning. The second round finished on Friday despite afternoon times being delayed for over two hours.
Romero, who played 27 holes on Friday due to Thursday's delay, got off to a hot start on his second round with a birdie on No. 10, his first. He came right back with birdies on 11 and 12 on the Albatross Course at Le Golf National to move to minus-4.
The Argentinean holed out from a greenside bunker for birdie on the par-5 14th. Romero rolled in a 12-foot birdie putt from the back fringe at the par-3 16th.
The 50-year-old drained a 20-foot birdie try on 18 to make the turn at minus-7. Romero's 29 on his first nine holes was the best nine-hole score of his European Tour career.
Romero, who won this title in 1991, parred the first four holes of his back nine. He then rolled in an 8-foot birdie putt on the fifth, his 14th, to get to 8 under. Romero birdied Nos. 7 and 8, both from within 15 feet, to establish a new course record by two strokes.
Romero's last win on the European Tour came at the 2002 Scottish Open.
With a win or a second-place finish this week, Romero would gain entry into this year's British Open Championship. He is scheduled to play the 36-hole qualifier at Sunningdale on Monday.
'I managed to qualify last year at Sunningdale in a playoff, but it's another year on now and it might be too much for me,' said Romero, who matched his best European Tour round with his 62. 'So I want to win here.'
Van de Velde birdied three of his first six holes to get to 10 under and a share of the lead with Romero. However, the Frenchman played his final 12 holes at plus-2 with two bogeys and 10 pars.
Lomas opened with a birdie on the first, but tripped to a bogey on No. 2. The Englishman converted consecutive birdies tries from the third to move to 8 under. After a birdie on the sixth, he bogeyed seven and nine.
The 37-year-old got one of those strokes back with a birdie on the 10th. Lomas moved back to 9 under with a birdie at the 14th. He fell back to 8 under with a bogey on the 17th.
Hansen ran off three straight birdies from the 12th to jump to 9 under. However, he faltered to a double bogey on the 15th and a bogey on 16. Around the turn, he birdied the first and third to get back into a share for second. He parred his final six holes.
Jean-Francois Remesy moved into a tie for seventh at 5-under-par 137 after a 2-under 69. He was joined there by Niclas Fasth, Peter O'Malley and Marcel Siem.
The cut line fell at 2-over-par 144 with 85 players advancing to the weekend. A pair of Frenchmen, Gregory Bourdy and Raphael Jacquelin, missed the cut by a single stroke.