Beware of Hillary’s collapse in the polls! It may be the very thing she needs to catalyze a gain.

Because both Trump and Clinton have very high negatives, this race is assuming a “see saw” pattern where one candidate’s success catalyzes a move toward his opponent.

When polls show Hillary ahead, people groan and focus on her scandals and wonder how this woman could be elected. But when they show Trump ahead, anxiety rises about what kind of president Donald would be and his worst quotes — often out of context — come back to haunt him.

This is a dangerous election in which to have the lead.

This happened in the 1980 Democratic Primary of Jimmy Carter vs. Ted Kennedy. Whenever Kennedy won a primary, people would recoil in horror at the events of Chappaquiddick and Carter would win the following week. Then voters would remember the hostage crisis and Kennedy would win the next round.

It’s happening now:

• After Trump’s good convention, voters panicked at the idea of a Trump presidency and Clinton took the lead

• After Trump was disciplined for a while in August and early September and Hillary collapsed on 9/11 and the FBI report came out, Trump took the lead as voters became fearful of a Hillary presidency.

• Then Trump did not do well in the first debate at the end of September and Hillary gained as Donald obsessed on Miss Universe. Stories of Trump’s resurgence doubtless contributed to Hillary’s gain as people focused on what kind of a president Donald would be.

• As the second debate approached and Trump stopped making mistakes and focused on message, he began to overtake Hillary in early October

• His progress was abruptly halted by the sex tape, and, despite a good performance by Trump in the second debate, Hillary took the lead again as she drowned Donald in a parade of women/accusers who stimulated fears of female voters about Trump.

• As the women faded from view and the conventional wisdom took hold that Hillary and all but won, Trump came back in the next week as her e mails and Doug Band’s memo and ObamaCare’s rate increases propelled his vote. Again, voters looked at a Hillary win and recoiled in horror.

• Now the e mail announcement by the FBI may alter the conventional wisdom and make people believe Donald will win. This might trigger a gain for Hillary in the final days.

The solution is for Trump to avoid triumphalism in public. He needs to be very respectful of Hillary’s political standing and his team needs to talk down expectations. No bragging or boasting. To do so would be to rivet attention on Trump’s own negative and give Hillary the running room to come back. Trump’s team needs to continue to say she is ahead even as polls show the opposite. They must continue to express doubts about the outcome and hold Donald back from public predictions of victory.