When Illinois voters head to the polls Tuesday to select the man or woman they want to send to the White House, experts said they should also select their candidate’s delegates for their vote to really matter.

Illinois has 19 districts and the number of delegates in each of them varies. Champaign County residents are in the 15th Congressional District where the Democratic and Republican parties each have four delegates that will go to their party’s convention.

The delegate system works differently between the Republican and Democratic parties and Green Party primary voters do not vote for delegates at all.

The presidential candidates and their delegates are on both the Republican and Democratic ballots. The presidential candidate’s name is on the ballot to reflect a preference for the person a voter wants to select for president.

But the real voting power is actually in the hands of the delegate, which is more crucial for Republican primary voters.

If a voter selects a Republican ballot and chooses the presidential candidate but none of his delegates, “You really haven’t done a whole lot to help your guy,” said Ken Menzel, Illinois State Board Elections expert.

Menzel said the delegates of either party that go to their convention and ultimately choose the presidential nominee, not the voter. Primary voters elect the delegates from either party, he added.

The Republican nominee needs 1,191 delegates and Illinois has 70 of them.

Menzel said the number of votes a Republican candidate gets in the presidential preference section does not affect the number of delegates that go to the convention.

“If Mitt Romney gets 50 percent of the Illinois vote in the presidential preference portion, but in (the 15th congressional district) the four people with the highest (delegate) votes are committed to Giuliani, the four Giuliani delegates go to the (Republican National) convention,” Menzel said.

Menzel said he understands when voters ask why the Republican ballot has a presidential preference on the ballot if it is not connected to the delegates.

“That’s a good question. It’s what they call a beauty contest,” Menzel said.

But this is not how delegates work in the Democratic primary.

Menzel said the presidential preference portion for the Democratic ballot is much more significant.

“If you vote for Obama and none of his delegates, your vote still goes to determining what percentage of the delegates Obama gets,” Menzel said.

“Let’s say Sen. Obama gets 50 percent of the vote, Sen. Clinton gets 25 percent of the vote and Mr. Edwards gets 25 percent of the vote. By getting 50 percent of the vote, Mr. Obama gets 50 percent of the delegates out of the district. By getting 25 percent of the vote, Clinton and Edwards would each get 25 percent of the delegates,” Menzel said. “For delegates, that would give Obama two, Clinton one and Edwards one.”

The Democratic presidential nominee needs 2,025 delegates nationally to earn the party’s nomination and Illinois has 185 of them.

Barack Obama delegate State Sen. Mike Frerichs said this system helps candidates win as many delegates as possible.

“Even though it looks like Obama is going to win Illinois, we want to run up the score so that he can get all of the delegates,” Frerichs said.

Menzer said while delegates of either party must commit to their presidential candidate at the convention during the first round of voting, they can change their minds afterward.

“If (delegates) go to the convention and (no candidate) has more than half of the delegates, they vote the way they are committed the first time and then they are essentially free agents,” Menzer said. “They can vote for somebody else the next time around.”

John McCain delegate Dave Kelm said while he is committed to using his delegate power to vote for McCain at the National Republican Convention, he does not have to do so.

“Delegates elected for a particular candidate are not legally bound to vote in that way,” Kelm said. “Honestly, I’m standing here at a John McCain event in Villa Park, Ill. I’m going to be voting for the guy if I go to the convention.”

Green Party voters will have four candidates from whom to select a nominee for president. But Green Party primary voters will not elect delegates. Menzer said delegates are selected by the Green Party at the state convention. Voters who do not associate themselves with either party would be limited to voting on any referenda or other ballot issues.

If voters want to vote for a write-in candidate or themselves, Illinois law requires anyone who wishes to be a write-in candidate to file a declaration of intent to be a write-in candidate at least 61 days prior to the election, Menzer said. But the write-in candidate must choose a party ballot on which he or she wants his or her name to appear.

The highest number of delegates Democratic and Republican candidates can win in one day is on Super Tuesday.

Democratic nominees will compete for 2,075 delegates on Super Tuesday while Republicans will compete for 1,081.