Prime Minister Recep Tayyip Erdoğan's ruling AK Party is widely expected to secure a third consecutive victory in the election, with opinion polls putting its level of support at around 45 percent.
But the second wave of resignations from the MHP could affect the parliamentary arithmetic -- it is not certain that the MHP will exceed the 10 percent threshold needed to retain their place in parliament.
Support for the MHP is around 10-15 percent, pollsters say. It was unclear whether the video controversy and resignations would affect its support among voters. The MHP has some 70 seats in the 550 seat parliament.
The failure of the MHP enter parliament could benefit the AK Party, with disenchanted MHP voters potentially turning to other right-wing parties.
MHP leader Devlet Bahçeli, who appeared deflated on Saturday as he addressed an election rally of several thousand similarly despondent looking supporters in the central Turkish province of Nevşehir, put a brave face on the resignations.
"Those who have resigned may have been aiming to make it easier for the party. We are continuing our struggle," he said before the rally.
The MHP resignations were triggered by the broadcast on a website of secretly filmed videos which purportedly showed senior members of the party involved in extra-marital affairs and making politically compromising statements.
The latest resignations brought to 10 the number of senior MHP party members to resign over the video scandal.
The "Different Idealism" website, an allusion to the "Idealist" movement which forms the backbone of MHP support, had threatened to broadcast further compromising video recordings if party leader Bahçeli did not resign by a deadline of May 18. He has not resigned.
It was not clear who was behind the website.
State-run Anatolian news agency said deputy chairmen Osman Çakır, Ümit Şafak and Mehmet Ekici, along with General-Secretary Cihan Paçacı and his deputy Mehmet Taytak resigned their party membership and candidacies to be members of parliament.
Another deputy chairman, Deniz Bölükbaşı, subsequently added his resignation.
"I have resigned ... to prevent these conspiracies and fake allegations triggering disputes which could harm the MHP going into the elections," Bölükbaşı said in a written statement. He said dark forces at home and abroad were behind "this ugly political conspiracy".
Broadcaster CNN Turk said the telecommunications authority had launched an investigation into the videos.
Arch-nationalist Alparslan Türkeş founded the MHP in 1969. Its supporters became embroiled in a conflict with leftists in the 1970s which was seen as helping create the climate which led to a military coup in 1980.