Bernard Reich, author of three books about United States-Israeli ties says it is a key factor which is growing in strength.
"It's a factor, it's there, it's not going to go any place; it's even getting stronger because the size of this Christian community is growing," Reich said.
With the next presidential election looming, the size of the Christian conservative establishment is estimated at a hefty 55 million people, making them a key campaign "target" - 10 times greater in number than the US Jewish population.
Having emerged as a well-oiled lobbying machine, the Christian conservatives are a high-profile presence in the halls of Congress.
They regularly have the ear of White House officials and put pro-Israeli advertising spots on national and cable networks.
Gary Bauer, a conservative Christian, former presidential hopeful and staunch pro-Israeli activist, often pens open letters to Bush, who is a Methodist Protestant, encouraging him to support Israel.
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than ever for pro-Israel groups
Ministers regularly raise funds for Israel and send charter jets with pilgrims seeking to "walk in Jesus' footsteps".
A group of evangelists in South Carolina recently went so far as to pay for a billboard on a Tel Aviv highway arguing against "land for peace" - a stand dear to Israel's ultra-conservative sections.
Israeli Tourism Minister Benny Elon, a leader of National Union (representing the ultra-conservative Jews) which has eight of the Knesset's 120 seats, has been among those campaigning in favour of Christian pilgrimages to the “promised land”.
Elon stressed that "what links me to Christians is deeper than what separates me from them”.
According to Reich, this is a very significant phenomenon because it's incredibly widespread and it comes from a portion of the US community with which Israel has very little else in common.
Conservative Christians like Bush believe Christ cannot return to earth to announce the end of the world as we know it until the Jewish people have rebuilt the Third Temple of Jerusalem.
The first was destroyed by the Babylonians in 587 BC, the second by the Romans in 70 AD, Reich said, adding that “for those Christians and for George Bush, it's a genuine religious belief”.