Many foreigners and an unknown number of Ukrainians want President Petro Poroshenko to be re-elected on March 31. But in doing so, no one must be allowed to trample on the greater principle at stake: The right of 35.9 million registered Ukrainian voters to choose their next president in an honest and transparent contest. If Poroshenko is to be re-elected, it should be done fairly and squarely. (Again, the Kyiv Post is not planning to endorse any candidate.)

Already, Ukraine faces several impediments to a free and fair contest: oligarchic control of the news media, a flood of untraceable and unaccountable money being spent by the 42 candidates and more. Ukraine has had a difficult history with elections, although it remains a beacon of democracy compared to much of the rest of the former Soviet empire.

In 1999, the unpopular ex-President Leonid Kuchma cheated his way to re-election. He was caught on tape directing regional political leaders to deliver certain vote margins to him. No one was punished, of course.

Kuchma limped to the finish line of his sad presidency and tried to install Viktor Yanukovych as his successor. The rigged election, with mysteriously changed vote totals by a secret server, triggered the 2004 Orange Revolution. The fraud allegedly had many co-conspirators, including Kuchma’s former chief of staff, Viktor Medvedchuk. But as always, the charges were denied and nothing was proven in court. Viktor Yushchenko won the re-run vote on Dec. 26, 2004, but his single term in office was mired by corruption and incompetence.

After 95 percent of voters rejected Yushchenko’s re-election bid, the choice became between two prime ministers — Yanukovych and Yulia Tymoshenko — in the 2010 runoff. Tymoshenko lost by 3.5 percentage points. In 2014, amid Russia’s invasion, voters picked Poroshenko over Tymoshenko in a landslide.

In this year’s contest, some of the same threats to a free and fair vote are resurfacing. There is concern that Poroshenko has created local fiefdoms among the big-city mayors of Odesa, Kharkiv and Dnipro and elsewhere in exchange for loyalty. Tymoshenko accuses him of vote-buying; he accuses her of dishonesty. It appears that only two candidates— Poroshenko and Tymoshenko — have enough observers to send to all polling stations nationally to spot voter fraud. But these are not neutral observers.

This is why credible international and professional election observation missions are essential. The preeminent expertise in this area belongs to the 57-nation Organization for Security and Cooperation in Europe’s Office of Democratic Institutions & Human Rights, known as ODIHR. It has a professional staff and a comprehensive methodology for assessing all aspects of elections — voter registration, media monitoring, election financing and the “vote audit” needed to ensure an honest count. Like in all elections, there will be violations and cheating. But what matters is whether the result of the election reflects the honest will of the people.

ODIHR set up a 17-member core team of experts, headed by Swedish Ambassador Peter Tejler, on Feb. 6, in Kyiv. It is expected to deploy 100 long-term observers and 750 short-term observers.

This mission, however, is caught up in controversy because of the requested presence of two Russian observers. There are some who say the OSCE mission should be kicked out if Russian citizens take part. But this is an invitation to election fraud.

On Jan. 25, we editorialized that Russia’s membership in the OSCE should be suspended because of its failure to live up to its democratic commitments, including its invasion of Ukraine and occupation of Crimea and the eastern Donbas. We also said that Russians should not be allowed on the mission. We stand by our positions.

But ultimately the OSCE mission must stay, with or without Russian observers, banned by parliament on Feb. 7. One solution is to deny the two Russians work visas to participate. It’s happened before in other nations. But we agree with U.S. special representative to Ukraine Kurt Volker that the overriding importance is to have the OSCE mission. He tweeted: “Ukraine needs ODIHR monitors to prove it adheres to democratic standards. Otherwise allows people to question election. OK if Russian monitors are part, but under ODIHR authority. No games. Ukraine needs to have confidence in its own democratic institutions.” Precisely.