Can Clinton grow lead in Iowa?

Odds are Hillary Clinton won’t match the Iowa Poll numbers released Monday, more than seven months before the caucuses. Her candidacy for president receives the support of 57 percent of likely Democratic caucusgoers in Iowa.

History suggests that’s as good as it gets for Clinton, and she has nowhere to go but down in her race for the Iowa caucuses. Her own campaign pointed out in a news release Monday that no candidate other than a sitting president, vice president (Al Gore) or home-state senator (Tom Harkin) has ever received more than 50 percent support in the caucuses.

That sounds like an effort to tamp down expectations: Don’t expect Clinton, a former first lady, former senator and former secretary of state, to do better than 50 percent. However, Clinton has a better chance to exceed that mark than most other caucus contenders in Iowa history.

Gore received 63 percent in 2000. His lone opponent, former New Jersey Sen. Bill Bradley, received 35 percent. Harkin, who ran in 1992, had 76.4 percent. Several other candidates received support in single digits that year but did not campaign seriously in Iowa.

The only other candidate other than an unopposed president to come close to 50 percent in the caucuses was former Vice President Walter Mondale, who ended with 48.9 percent despite being one of eight candidates in contention. Clinton won’t face that much competition.

Besides Clinton, there are two other announced candidates for the Democratic nomination. Vermont Sen. Bernie Sanders has 16 percent in the new Des Moines Register/Bloomberg Politics Iowa Poll. If Sanders becomes the progressive alternative to Clinton, he could whittle down her lead in Iowa.

Former Maryland Gov. Martin O’Malley, who announced his candidacy Saturday, has only 2 percent in the Iowa Poll. Despite significant time in Iowa during and after the 2014 campaign cycle, he’s failed to get much going here.

Vice President Joe Biden, who has not made any public moves toward running, has 8 percent in the Iowa Poll, but would be the second choice of 31 percent of likely Democratic caucusgoers. Former Virginia Sen. Jim Webb, who formed an exploratory committee, is also at 2 percent in the poll.

It may seem improbable, but there is room for Clinton’s support to grow between now and caucus time. The former secretary of state is the second choice of 15 percent of likely Democratic caucusgoers. Another 14 percent are either uncommitted or not sure of their first choice.

Keep in mind, also, that the rules for Iowa Democratic caucuses tend to magnify the front-runners’ support. Under the rules for delegate apportionment, candidates need to attract a minimum percentage of support in each precinct. Candidates who don’t make the viability threshold tend to lose supporters to a stronger campaign, which inflates the winner’s margin on caucus night.

The new Iowa Poll points out some of Clinton’s weaknesses. Most likely Democratic caucusgoers say they are unfazed by Clinton’s use of private email as secretary of state, her handling of the Benghazi attacks and the Clinton Foundation’s foreign donations. But 66 percent of likely caucusgoers say one or more of these issues will hurt Clinton in the general election.

The more Clinton travels the state and answers questions from voters and yes, the media, the better opportunity she has to manage those concerns and others that will arise. There’s no express elevator to the top of the Iowa caucuses — only a long staircase that must be climbed a step at a time.

Clinton is scheduled to return to Iowa after her campaign kickoff rally June 13 in New York City. Her campaign says she will attend a campaign organizing event in Iowa, but no word yet on where it will be or who may attend.

The Des Moines Register/Bloomberg Politics Iowa Poll of 437 likely Democratic caucusgoers was taken May 25-29 by Selzer & Co. It has a maximum margin of error of plus or minus 4.7 percentage points.