Why Saudi Arabia sees Iran as its biggest rival in the region?

Saudi Arabia does not exist on its own and does not act on its own , and  is an Arab and Muslim country only in name.  KSA is part  the World Order , and is a  US military base and does US bidding. The rivalry therefore is not between KSA and the Islamic Republic , the enmity is between USA and Iran because Iran refuses to subscribe to the World Order agenda  and is trying to build its independence and sovereignty and helping others do the same. Iran does not bear enmity to KSA for it knows that KSA is not its own master. Therefore, there is no rivalry between the two, and whether Iran or KSA,  they have nothing to fight over and there is no sectarian war  nor anything of this sort happening between them. This is all made up. But the sectarian alignment created by KSA upon US request  comes in handy in order to take the struggle somewhere else away from the Arab /  Israeli struggle.  The truth is that there is a world Order and US agenda that Iran is successfully challenging . For this reason, KSA and USA and Israel and others have rallied against Iran.

How much influence the Saudis have in the United States? Can they urge Washington to impose more sanctions against Iran?

The Saudis have money,   but their influence in the United States is not in proportion to their wealth . Saudis have influence in poor countries like Pakistan and in Arab countries like Lebanon and Jordan and Sudan  . They have a say in these countries to a great extent  as much as US permits . and  they have to get  the US approval for everything they do or intend to do in the region if they intend to do anything . In general,  Saudis carry on US orders,  but US has everything to gain from having KSA look as if it enjoyed  some sort of independence .Thus,  all ugly deeds are attributed to Saudis .  Saudis have become the black sheep,  and now they are being accused in the Media of creating and nurturing Terror,  and of being behind the 9/11 attacks which is only partly true.  The truth is that USA needs to hide behind someone and KSA will fill in this role as much as needed .

What is the Saudi regime doing to hamper Iran’s bid for more economical power?

First the Saudis upon US request decided to increase the production of oil which caused the oil prices to drop drastically . This was meant to hurt Iran and others countries were hurt in the process   like Venezuela for example . But KSA was hurt as well which means that this could not have been a KSA  decision but a US decision. KSA does not want anything but to please its US master , it is USA that wants and KSA executes.

How do other Arab states in the region, say the UAE, react to the rivalry between Iran and Saudi Arabia? How willing are they to support Saudi Arabia?

The UAE are willing to support the KSA all the way and they are waging this war together on Yemen ,and UAE is not different from KSA and now is in full control of the south of Yemen after the Ansarullah have withdrawn from there , and the UAE has invaded with  its mercenaries and has controlled the south with the intention of separating it from the north . Whether KSA or UAE  , they both carry the western agenda  and they will not be allowed to have any positive exchange with Iran even if they wanted to.

Have Saudis been successful in curbing Iran’s influence in the region? If not, what else can they do?

The Saudis  have not succeeded in anything , it is US that used the Saudis in order to create the sectarian alignment that was meant to undermine the forces of the Resistance and to weaken Iran .They have succeeded in destroying Syria and Iraq,  and they have succeeded in fueling sectarian hatred but they cannot curb Iran's influence because Iran draws its strength from itself and not from any sectarian or fanatic stand .They are still trying and only God knows what they will try . They are now trying to play on the Kurdish element to create a Kurdish separatism that they hope will reach Iran,  and they will try hard to infiltrate the Iranian society by different means, to sway the Iranian youth from its path and its duties by exposing it to their culture and patterns of behavior  , but they will fail also . As long as there is vigilance and openness as long as wisdom rules Iran , as long as Religion is alive , there is no fear . They will fail because Iran knows them and is aware of their conspiracies and schemes.

How does the nuclear deal affect U.S.-Saudi relations?

The nuclear deal is the result of the failure  of the US in curbing Iran.

Because USA knew that it cannot wage war on Iran nor defeat Iran so they chose the best way out of this dilemma by striking a deal with Iran that was the best they could come up with  . This deal shows the defeat of the USA , the military defeat of the USA . As for how the relations with Iran will be affected . they will remain the same and will not improve  unless US changes  and becomes something else . Iran does not bear enmity to any country but it will not allow any country to infringe on its inborn legitimate rights as a sovereign country .