Caliphate before Mahdi?

As Salamu Alaykum My question is will the Mahdi restore the Caliphate
or will the Caliphate be retsored before he comes are there diffrent interpretations or opinions or views according to Hadiths before Day of Judement Last and Anti Christ coming thank you ?

Al-Mahdi (the Mahdi)
1. Sunni Muslims' Al-Mahdi (Mehdi)
2. Signs before the Mahdi
3. Roman (European) Invasions of the lands of Muslims & the Conquest of Constantinople & Rome by Muslims
4. Other Wars & Events around the time of the Mahdi(s)This includesa)internal fighting & bloodshed in the Muslim World, (b) the Mahdi's fighting against Iran, (c) invasions by the Turks (Russians), (d) fighting the Andalusians, and Abyssinians (Ethiopians & East Africans),(e) Muslims' conquest of India, etc.
5. Could Muslims could be ruled by a series of Caliphs, not just the Mahdi ?
6. Similarities between Shia's Imam Mahdi & the Anti-Christ Shia's Imam Mahdi is likely to be the Anti-Christ

http://www.discoveringislam.org/the_mahdi.htm

reaz rujub says:
May 15, 2011 at 5:28 am
It is known that Caliphate will be established after the appearance of Al Mahdi. So how come the first Hadith say that disagreement will occur at the death of a caliph and then Al Mahdi will appear? The simple answer is that, maybe, the Hadith is only talking about an ordinary leader who is not in the right path of Allah . If this is right, it may be that it is refering to Bin Laden, as disagreements have surely occured in the Ummah due to his death. Or, it may be that this Hadith is refering to Ahmadinejad, and his future death, which may surely cause disagreements. And Allah and His Messenger know best.



http://www.jihadica.com/mahdi-will-appear-after-return-and-death-of-caliph/

Al-Mahdi & A Caliphate That Follows the Guidance of the Prophet (saws)
by A. Hijazi

Hudhaifah bin Al-Yaman reported that the Messenger of Allah sallallahu `alayhi wa sallam said,
"Prophethood (meaning himself) will remain with you for as long as Allah wills it to remain, then Allah will raise it up wherever he wills to raise it up. Afterwards, there will be a Caliphate that follows the guidance of Prophethood remaining with you for as long as Allah wills it to remain. Then, He will raise it up whenever He wills to raise it up. Afterwards, there will be a reign of violently oppressive [The reign of Muslim kings who are partially unjust] rule and it will remain with you for as long as Allah wills it to remain. Then, there will be a reign of tyrannical rule and it will remain for as long as Allah wills it to remain. Then, Allah will raise it up whenever He wills to raise it up. Then, there will be a Caliphate that follows the guidance of Prophethood."
Then Hudhaifah said, "The Prophet stopped speaking." [As-Silsilah As-Sahihah, vol. 1, no. 5]

http://www.islaam.net/main/display.php?id=1107