Donald Trump at West Chester University

Donald Trump speaks to a large crowd at West Chester University in West Chester, Pa., Apr. 25, 2016. Mark Pynes | mpynes@pennlive.com

(Mark Pynes | mpynes@pennlive.com)

By Tom Ridge

The golf bag I lugged around for 18 holes at the Lake Shore Country Club in Erie was heavier than any bag I've carried since.

Former Pennsylvania Gov. Tom Ridge

While I was just 13 at the time, those days working as a caddie left a lasting impression - and not just on my back!

That bag belonged to the chairman of the Erie County Republican Party, a man who played a major role in my eventually becoming a lifelong Republican.

My dad, also named Tom Ridge, was so much a Democrat that he once changed his party registration so he could vote for his son in the GOP primary.

Then, at the first opportunity, he changed it right back. I said, "Dad, stay a while!" Mom was a Republican.

You can imagine our dinner conversations. But we were always respectful of each other's beliefs. One of the valuable lessons was that neither party enjoyed the wisdom of Solomon nor had all the answers of an oracle.

The Republican Party is another family to me - a family to which I have proudly belonged for some 50 years.

Every four years since my 18th birthday, I have pulled the lever in support of the Republican nominee for President of the United States. That streak will end this November.

My disregard for Donald Trump has been well documented by multiple media outlets over the last several months, so I won't belabor it yet again. Suffice to say that I am disappointed that he is our party's nominee.

With a bumper sticker approach to policy, his bombastic tone reflects the traits of a bully, not an American president and statesman. If he cannot unite Republicans, how can he unite America? I simply cannot endorse him.

Similarly, I cannot support Hillary Clinton, a divisive and untrustworthy candidate who will advance and extend failed Obama policies that have greatly weakened our nation's economy and security.

I share this with you because, as a former governor and federal cabinet secretary, inquisitive journalists routinely ask me to which candidate I'll be lending my support.

Over the next six months I have chosen to focus my energies not on the presidency, but on maintaining Republican control of the U.S. House of Representatives and the Senate. There are a number of outstanding conservative candidates facing tough reelection battles in critical House and Senate races.

So I intend to work hard to reelect friends like Sens. Rob Portman of Ohio and Pat Toomey of Pennsylvania. These two men represent the best of the Republican Party - at least the party I have come to know and love - and are deserving of another term.

They both not only have solid conservative credentials, but also have demonstrated an ability to work across party lines to get things done on behalf of their constituents. In other words, governing.

While it is hard to imagine either nominee for president doing the same, Rob and Pat have a proven record of doing just that. We will need their steady and proven leadership in the uncertain years ahead.

Two Republican presidents changed my life in a very personal and meaningful way. One called on me to serve my country in Vietnam; the other asked me to serve my country after the attacks on 9/11. Neither president asked me my position on the issues of the day. In both instances, the message was simply: "Your country needs you - please serve." And I was privileged to serve in Congress under a principled yet gracious Republican president - Ronald Reagan.

The voter appeal of Reagan's big tent was that, maybe, inside that tent, politics might not take precedence over the business of governing - of getting things done.

That appeal swept him into office - and kept him there - because he had a vision. And while he was as deft a politician as we've ever had, he was a leader first, a likable man second, a politician third.

He ran on the vision of a "shining city on a hill," tapping into the innate optimism for the future that he shared with the American people.

Reagan knew, as Teddy Roosevelt knew, as Lincoln knew - that beyond politics, a party must be about purpose.

Americans are going to decide in November who will be our next president. While I cannot endorse either candidate, whoever wins will be my president, too. And so I will help to advance their success in any way that I can.

Because while I began to learn what it means to be a Republican carrying that heavy bag so many years ago, my years in public service have only served to affirm that duty and loyalty to our nation must always come first.

Tom Ridge, a Republican, was Pennsylvania's 43rd governor. He was the nation's first Homeland Security Secretary and currently serves as CEO of Ridge Global. This piece first appeared on U.S. News.